Berkshire's Best—The A-S 55

by Adrian Duncan

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Here we take a look at one of the nicest and most useable small diesels ever manufactured in England—the A-S 55 of 0.55cc displacement. This fine little unit was the last of the classic British "1/2 cc" diesels of the mid 20th century which had been heralded in late 1950 with the appearance of the Allbon Dart. In the opinion of many, myself included, it was also the best of those classics. Let's have a look at this engine, beginning with the chain of circumstances leading up to its introduction.

Background

The designer of the A-S 55 was Alan L Allbon, about whose personal background my extensive research has turned up absolutely nothing. However, Allbon's career as a model engine designer is very well documented. There's no question that Allbon was one of the most experienced commercial model engine designers in Britain at the time when the A-S 55 was developed. As it turned out, the A-S 55 was significant in being Allbon's final effort in the model engine design field before he moved on to other interests.

Allbon began marketing his own model engine line under the Allbon Engineering banner in 1948. The Allbon engines were initially manufactured at a small plant located at 51A Thames Street, Sunbury-on-Thames, Surrey, a little to the west of London. Sunbury-on-Thames lies today in the county of Surrey, although prior to the 1965 county boundary reorganization resulting from the Royal Commission on Local Government in Greater London it was located in Middlesex. Regardless, the community lies just across the River Thames from the successive haunts of Electronic Developments Ltd at Kingston-on-Thames, West Molesey and Surbiton, and not all that far from the International Model Aircraft (IMA) plant just to the east at Merton, where the FROG range was manufactured. The model engine industry was a significant employer in South-West London in 1948! Think of the craic in all those engine-maker's pubs ...

Thames Street has moved well upmarket since Allbon's time there, many of the buildings on the street having been converted into flats, restaurants or office space. The red brick building at 51 Thames Street, which may well be the one formerly occupied by Allbon, is today (2012) occupied by a branch office of A. A. Telecom Ltd. Looking at the building and the location as they appear today, it seems not unlikely that this was Allbon's residence as well as his business location.

The Allbon model engine range got its start with two successive variants of a very workmanlike 2.8cc sideport diesel. The range was soon augmented by the successive appearances of the 1.5cc Arrow glow-plug motor, the Mk. I version of the famous 1.5cc Javelin model, which was a highly-regarded diesel version of the not-so-successful and short-lived Arrow, and the 0.55cc Dart Mk. I diesel. Dennis Allen was associated with the Allbon venture during this early period.

The Dart was introduced in late 1950, and its immediate and overwhelming popularity forced Allbon to limit production of other models, the Arrow in fact joining the 2.8cc model in being dropped altogether. Even with these changes to the production schedule, demand for the Dart evidently outstripped Allbon's ability to produce it at his existing facility. Indeed, the immediate success of the engine prompted the speedy development of competing 1/2 cc diesel models by no fewer than three other British manufacturers—ED, Elfin, and International Model Aircraft (FROG).

The introduction of domestic competition did little to moderate consumer acceptance of the Dart. The Elfin 50 and FROG 50 models fell by the wayside fairly early on for one reason or another, but both the Dart and the 0.46cc ED Baby went on to enjoy extended production lives. The Dart in fact survived in its later Davies-Charlton form until 1984, when a 34-year production run finally ended. This made it one of the longest-running continuous productions in British model engine history—only the PAW range can show anything approaching a matching record. It must however be said in passing that the later Davies-Charlton versions were a pale reflection of the Allbon originals.

As a result of the Dart's success, by mid 1951 Allbon found himself faced with a significant challenge—he had an extremely successful product but was unable to manufacture it at a rate which came close to meeting the demand. Moreover, he was in no position either to expand his range or even maintain production of the companion Javelin at levels which matched the considerable demand for that model also. In effect, Allbon had fallen victim to his own success as a model engine designer! This situation prompted him to enter into discussions with Davies-Charlton Ltd. of Barnoldswick in Lancashire regarding the possible mutual benefits of some level of cooperation.

The initial consequence of these discussions was Allbon's late 1951 closure of his Sunbury-on-Thames facility. By January 1952 he was advertising his products from a far more bucolic address at The Forge in Cople, which is a small rural community of some 700 people lying out in the countryside to the south-east of Bedford. Interestingly, the only model advertised by Allbon during almost all of 1952 was the Dart, implying that production of the Mk. I Javelin had followed the Arrow in being suspended while Allbon's manufacturing arrangements were being reorganized to meet demand for the Dart.

Initially there was no mention of any involvement on the part of Davies-Charlton (who continued to advertise separately), creating an impression that the Allbon engines were still being independently manufactured by Allbon Engineering, albeit at the Cople location. However, in his "Accent on Power" column in the April 1952 issue of Model Aircraft, Peter Chinn let slip the fact that the manufacture of the Dart had actually been taken over by Davies-Charlton. It appears that Allbon had simply closed his Sunbury workshops and moved his residence and his business office to the pleasant rural surroundings of Cople, leaving Davies-Charlton with the job of actually making the engines.

It's significant that during this period Allbon continued to advertise independently from his Cople location under the Allbon Engineering banner, while Davies-Charlton in turn continued to advertise their own distinct range from the Barnoldswick address. The clear implication is that at this stage no actual merger of the two companies had taken place, the relationship being purely contractual. However, the arrangement must have worked out well for both parties, since the next step towards a full merger was the combination of the distribution arrangements for the Allbon and D-C ranges. This was a logical move given the fact that the Dart was in reality being manufactured by Davies-Charlton despite Allbon's ongoing reluctance to openly admit this fact.

By April 1952, Allbon's advertisements were openly confirming that the distribution (as opposed to the manufacturing) of the Dart had been taken over by Davies-Charlton, although Allbon still continued to advertise separately from his Cople location and still stopped short of crediting Davies-Charlton with the actual manufacture of the Dart. Allbon was still advertising the Dart independently in October of 1952, but the distribution of both the Allbon and D-C ranges had by then been taken over by E. Keil & Co. This arrangement was to continue for some time following the completion of the merger.

The amalgamation of the two companies was apparently completed prior to the end of 1952. No more was heard of either Allbon Engineering or the Cople location, although it's quite possible that Allbon maintained both his residence and his design office there. Production of the Allbon engines by that name was now openly consolidated at Davies-Charlton's Barnoldswick plant in Lancashire along with that of the continuing Davies-Charlton models.

The merger allowed Davies-Charlton boss Hefin Davies to put most of his energies into leading the doubtless-lucrative contract work for Rolls-Royce and others which was a mainstay of Davies-Charlton's business plan at this time, while Allbon assumed primary responsibility for the subsidiary model engine development and production programs. It also allowed the expansion of the Allbon range at production levels which could be tailored to meet demand. Hence there were clear benefits for both parties.

Initially, the distinct identity of the two ranges was maintained, with Mk. II versions of both the Allbon Dart (now with a red head in place of the original green) and the Allbon Javelin appearing more or less concurrently with the merger, along with the newly-introduced 1cc Allbon Spitfire. Moreover, the Allbon name continued to be applied to other new designs as time went by, including the 0.15cc Allbon Bambi which was launched upon the marketplace in June 1954 and the very popular 0.76cc Allbon Merlin which appeared in October of that year. The collaboration between Davies and Allbon continued through Davies-Charlton's early 1955 move to the Isle of Man.

Meanwhile, the well-established 3.5cc D-C 350 models (diesel and glow) which had been introduced well prior to the merger carried on concurrently under the D-C banner. The 3.5cc Manxman which replaced the old D-C 350 in March of 1956 was also marketed from the outset as a Davies-Charlton product. It would appear from this that Alan Allbon had had little or nothing to do with the design of that model, which was after all based on a Hefin Davies design dating from well prior to the 1952 merger.

Although the Dart, the Merlin, the Spitfire and Sabre twins, and even the February 1957 Rapier were all initially marketed under the Allbon name, that name was progressively dropped thereafter, seemingly disappearing entirely in 1958 after lingering for a while on the company's diesel fuel labels. By all reports, Hefin Davies was not an easy man to work with, and it appears that a gulf progressively developed between Davies and Alan Allbon which eventually resulted in Allbon severing his connection with Davies-Charlton in early 1959. His departure was very much Davies-Charlton's loss, since it is from this time onwards that we can trace the steady erosion in quality which was to bedevil the D-C range in later years.

Following his departure from Davies-Charlton Ltd., Allbon made it immediately clear that he was by no means done with the model engine business. It's possible, albeit completely unproven at this point in time, that he felt that he had something to prove to Hefin Davies and that he saw the best way of going about this as being the introduction of his own successful design with which to compete with D-C Ltd. for sales.

The result was the introduction of our main subject, the A-S 55 diesel. Let's have a close look at this excellent little engine.

The A-S 55 Described

To anyone familiar with the Davies-Charlton range as it evolved during Alan Allbon's tenure there, the A-S 55 has an immediately familiar look about it. The engine displays relatively little in the way of original design thinking, embodying in effect a combination of the designs of the D-C Dart and the D-C Merlin ((as they were known by this time). Both of these models had originally been developed by Alan Allbon, so it comes as no surprise to find him borrowing from himself by combining what he evidently believed to be the best features of both models into his new offering. However, the A-S 55 did embody a number of features which set it apart from its D-C rivals.

Like its D-C and Allbon forebears, the A-S 55 was a completely conventional small sports diesel having the then-standard combination of a pressure die-cast crankcase, radial porting, crankshaft front rotary valve induction and a plain main bearing. Bore and stroke were equal at 0.350" each (8.89 mm) for a displacement of exactly 0.55cc (0.033 cuin.). Both of these dimensions were carried over directly from those of the Allbon-designed Dart. Weight of the illustrated example complete with tank and fuel tubing is 1.5 ounces (44 gm), exactly as claimed by the manufacturers.

The cast iron cylinder exhibits a combination of features carried over from the Dart and Merlin designs. Like that of the Merlin, it is not threaded at any point. It features a thin flange immediately below exhaust port level which seats on a shelf machined into the top of the main crankcase casting. The three sawn exhaust ports are cut immediately above this flange. Thus the main form of the cylinder follows the Merlin pattern, the exception being that the exhaust ports are cut above the locating flange rather than through it. The resulting thinner flange represents a saving in weight of the cylinder.

By contrast, the transfer porting adheres to the design of the Dart, bringing with it the advantage of allowing a degree of overlap between the transfer and exhaust ports. The three transfer ports are drilled from below the cylinder location flange to enter the bore at an upward angle between the exhaust ports, slightly overlapping those ports in doing so. The most noteworthy feature of the transfer ports is their very small size—only 1/16" diameter. This may be expected to result in relatively high transfer gas velocities, which are generally beneficial in terms of starting characteristics.

The cylinder liner is secured in a manner analogous to the Merlin using a separate alloy cooling jacket which is a plug fit over the upper cylinder. The inner diameter of the jacket is increased to accommodate the cylinder location flange, with the resulting shoulder bearing directly upon the upper surface of the flange immediately below the exhaust ports. This results in the cylinder liner above the flange being unaffected by installation stresses. A gasket is used below the flange to ensure a seal. Hopefully the attached close-up view of an exhaust port will clarify this description.

The lower portion of the jacket is internally threaded to match a set of male threads machined onto the upper crankcase casting. The assembly is thus identical to that used in the Merlin with the exception that the jacket threads externally over the upper main casting instead of internally as on the Merlin. In characteristic Allbon fashion, a pair of flats is machined into the upper part of the cooling jacket to facilitate tightening.

A noteworthy point is the care which was taken during assembly to match the exhaust ports in the liner with those in the cooling jacket. Three milled slots are provided in the lower jacket to allow for the passage of exhaust gasses, and in all examples that I have seen these slots have been carefully matched to the locations of the cylinder ports when the jacket is fully tightened, thus ensuring unrestricted gas passage. This would have required a degree of trial and error during assembly, and it's a convincing argument against dismantling a correctly-assembled engine unless there is a pressing need to do so. I have elected not to disturb my own near-pristine example.

As in the Merlin, the diameter of the lower cylinder below the location flange is turned substantially smaller than that of the interior of the upper crankcase casting, the cylinder being axially located solely by the locating flange and cooling jacket. The bypass passage is formed by the resulting 360 degree annular gap between the inner crankcase wall and the outer wall of the lower cylinder.

The piston and contra-piston are both of cast iron and are extremely well fitted to the bore. Somewhat unusually, the top of the piston is domed rather than being conical in form, the contra piston being dished to match. A forged alloy con-rod with un-bushed bearings is used in conjunction with a 3/32" diameter fully floating gudgeon pin. There is no sub-piston induction.

Unusually for a British diesel of this displacement, the hardened steel crankshaft has a counterbalanced web. Main journal diameter is a generous 0.239" which accommodates a 0.128" diameter central gas passage with ample strength. The circular induction port in the crankshaft is of 1/8" diameter. By contrast, the similarly-sized Dart used a crankshaft having a journal diameter of only .205" with an internal gas passage of 0.100 diameter. Since shaft breakages were not unknown with the Dart, this clearly represents a case of Alan Allbon learning by experience and making necessary improvements in his new design.

The backplate is very reminiscent of that used in the Merlin, being a pressure die-casting which is a plug fit in the rear of the crankcase and is secured by two screws, one at each side. Unlike the Merlin, these fastenings do not extend through the mounting lugs but are threaded into tapped holes at the rear of the engine mounting lugs. The latter are of the "twin expansion" form seen on the Merlin and its various Allbon-designed relatives.

The engine features a highly polished stamped metal tank which is secured by a central screw as on the Dart rather than being retained by the backplate retaining screws as in the case of the Merlin. This has ample capacity for free flight applications. The tank retaining screw is neatly countersunk—very elegant! The backplate is provided with a tapped central spigot to accept the screw, but is otherwise very similar to its Merlin counterpart.

At the front end, the shaft is an extremely accurate fit in the unbushed plain bearing which is reamed into the main casting. The prop driver is very well secured using a brass split collar in the conventional manner. The prop nut thread is 4 BA and is of ample length for the full range of airscrews which might be used.

The needle valve assembly is well worthy of comment. Unusually for such a small engine, the spraybar features a right-angled spigot at the fuel pick-up end. This keeps the fuel tubing very close to the main body of the engine without the risk of kinking, thus being a very welcome feature matched among contemporary small British engines only by the 0.46cc E.D. Baby. The needle valve itself has a split thimble for tension which gives the control a very smooth yet positive feel. All of the needle valve components other than the steel needle itself are machined from aluminium alloy.

The one criticism of this assembly is the fact that it is angled back to the right of the engine (looking forward in the direction of flight). While the angling makes the control very accessible to the fingers, it has the limitation that it cannot be reassembled on the left for sidewinder control-line use. This is an issue that seems to have escaped the attention of many British engine designers during the period in question. Odd, because many Continental makers did in fact angle their needle valves to the left...

All of the A-S 55 engines bore serial numbers. These were hand-engraved on the underside of the crankcase. My own illustrated example bears the serial number 1278. The boxes in which the engines were supplied had a panel on their end-face labels in which the serial number of the enclosed engine was hand-written, thus matching box to engine.

In summary, the A-S 55 may best be described as an amalgam of Dart and Merlin features which embodies the best elements of both designs in a very attractive package while adding a few improvements over both previous designs. Moreover, the engine is extremely well made, all fits being of the highest order throughout. Clearly this was a sincere and successful attempt by Alan Allbon and his partner to produced a real quality piece of modelling merchandise.

The A-S 55 On Test

It didn't take resident Aeromodeller tester Ron Warring long to get his hands on an example of the A-S 55 for testing. Warring's report appeared in the April 1960 issue of the magazine, only some five months after the engine's introduction. Allowing for the time required for testing and writing as well as editorial lead time, this was fairly quick work.

Overall, Warring's report was extremely complimentary. He began by drawing his readers' attention to Alan Allbon's long experience with model engine design and manufacture, going on to praise the latest Allbon design very highly. Starting was characterized as "easy" following a prime, and the engine was reported to run "strongly and smoothly" up to speeds well in excess of that at which peak power was developed. Response to both compression screw and needle valve was described as "not at all critical". Finally, the standard of workmanship was commended.

Peak power output was reached at a relatively moderate speed by small engine standards. However, the torque developed by the engine was clearly well above average for a design of this specification and displacement, since the actual peak recorded was unusually high for such a small plain bearing sports diesel. Warring recorded an output of 0.052 BHP @ 12,000 rpm. The peak power figure was well in line with outputs recorded by Warring for the three competing British .049 glow-plug models on which he had reported in January 1960, making the A-S 55 a direct competitor with those models for customers who preferred diesel operation. Moreover, this power was developed at significantly lower revs, allowing the use of larger and hence more efficient airscrews.

The specific output represented by this figure was very impressive for such a small engine. Specific outputs tended to fall with reduced displacements, making the 0.095 BHP/cc figure achieved by the A-S 55 quite impressive. This was at a time when makers of plain bearing sports diesels of any size struggled to beat the 0.100 BHP/cc figure. Many substantially larger contemporary diesels could not match the A-S 55 in this respect.

It's also interesting to compare this performance with that obtained by Warring in his April 1953 test of the D-C-built Allbon Dart Mk. II which was still in production in 1960 as the D-C Dart and was generally considered to be the 1/2 cc standard for performance. Warring reported a peak output of only 0.042 BHP @ 11,000 rpm for that model, somewhat down from the figure of 0.045 BHP @ 13,300 rpm measured by Lawrence Sparey in his January 1951 test of the Mk. I Dart. Interestingly enough, actual present-day experience with the Dart confirms that the original green-head Allbon-built Mk. I engines did have a higher performance than the later D-C-built Mk. II red head models.

Regardless, the A-S 55's larger crankshaft induction port was clearly effective in releasing more power. Even the 0.76cc Allbon Merlin could only manage an output of 0.058 BHP @ 13,000 rpm based on Warring's December 1954 test, yielding a substantially lower specific output figure of only 0.076 BHP/cc. The smaller A-S 55 came remarkably close to matching the output of the Merlin and was in fact more or less on a par with the larger engine up to 12,000 rpm or so. There's little doubt that the A-S 55 was the most powerful diesel of its displacement to be commercially manufactured in Britain prior to the far later advent of the PAW 55.

The fact that the engine developed unusually high torque for its size meant that the recommended airscrews were larger than one might expect. The manufacturers recommended 7x4, 6x6 and 6x4 airscrews for the A-S 55, sizes which appear well in line with the reported performance figures but are more typical of those generally applied to diesels in the 0.8cc category. Warring found that the engine turned a 7x4 FROG nylon prop at a very respectable 9,000 rpm and a 6x4 FROG nylon at 12,500 rpm. The latter figure was past the measured peak, indicating that the test engine would have been under-propped on the 6x4. The much faster D-C nylon 6x4 prop was even worse in this respect, since the engine got this up to 14,500 rpm. A cut-down 7x4 or an untrimmed 7x3 would likely have worked well for free flight applications. For control line, a 6x5 or the FROG nylon 5x6 would likely have been happy choices, since the engine turned the latter prop at 11,000 rpm on the bench.

Warring's overall summation was extremely complimentary. He characterized the A-S 55 as "an engine which pleases by its appearance, fine workmanship, good handling characteristics and admirable power rating for its capacity". Such a positive finding must have harmonized well with Allbon-Saunders' efforts to popularize the engine.

A further review by Model Aircraft tester Peter Chinn appeared in the June 1960 issue of that magazine. If anything, Chinn was even more complimentary than Warring in his assessment. He made the outright statement that "judging by our test sample, this is the best 1/2 cc diesel that has yet been offered to the British modeller". Chinn based this characterization on a combination of the engine's "excellent construction, easy starting and good performance". He went so far as to state that the A-S 55 was "one of the easiest starting diesels we have yet encountered". It may be imagined that the previously-mentioned small transfer ports and associated high transfer gas velocities had something to do with this.

The output recorded by Chinn was slightly less than that found by Warring—an unusual circumstance since Chinn generally tended to find more power than Warring in tests on the same engine. Moreover, Chinn found peak power to occur at substantially higher rpm than Warring, reporting a figure of 0.047 BHP @ 14,000 rpm. Clearly he extracted less torque from the engine than Warring. This may simply be a reflection of the undoubted fact that the effects on performance of incidental manufacturing differences between different examples of the same engine tend to be magnified with decreasing displacement. Regardless, the reported figures are still highly flattering to an engine of this displacement.

My own tests on the illustrated example of the engine have done nothing to contradict either Warring's or Chinn's findings. The engine is undoubtedly very well made indeed. It is also a notably easy starter and a fine runner with excellent control response and a very sprightly performance. The controls themselves are conveniently sized and positioned. Tests on examples of the contemporary props used by Warring which remain in my possession yield figures which are invariably within 100 rpm or so of Warring's data.

Production History

The establishment of a new model engine manufacturing venture inevitably required a significant outlay of capital. Allbon seem to have solved this problem by entering into partnership with a certain Mr. Saunders, about whom nothing seems to be known in an aeromodelling context. Reading between the lines, it's likely that Saunders brought capital and perhaps marketing expertise to the table, while Allbon brought his extensive hands-on experience of model engine design and manufacturing.

The new partnership was incorporated under the name Allbon-Saunders Ltd., trading from premises located in Milton, Berkshire. No street address was every given, posing problems for any owner wishing to contact the manufacturers directly regarding spares or warranty service. Subsequent research has uncovered the fact that the actual location of the Allbon-Saunders plant was on Pembroke Lane bordering the north edge of what is today (2012) the Milton Industrial Estate. At the time in question, Milton was a small rural community lying some 3 miles to the south of Abingdon. As of 1959 it seemed an unlikely location for a precision engineering company, but then so was Allbon's former location at Cople in Bedfordshire!

The design and tooling for the engine were developed in 1959 with the obvious goal of getting it onto the market in time for Christmas of that year. It appears that Allbon-Saunders were successful in meeting this goal. The initial announcement of the A-S 55 appeared in the "Motor Mart" feature of the November 1959 issue of Aeromodeller magazine, together with a photo of the engine. The introductory advertisement appeared in the December 1959 issue of the magazine.

The selling price of the engine was �2 15s 6d (�2.77 in modern money) inclusive of all taxes. This was quite a bit more than the cost of a number of contemporary competing models, particularly the new breed of British-made 1/2-A glow-plug motors which were appearing more or less concurrently. Presumably the manufacturers were hoping that the engine would recommend itself on merit regardless and/or would dissuade many diesel fanciers from switching their allegiance to glow.

As events were to prove, their confidence was justified to a degree. The A-S 55 was viewed very favourably by the modelling public, being widely considered to be the best "1/2 cc" model that had ever entered series production in Britain up to that time. The very positive test reports by Ron Warring and Peter Chinn could only have helped the cause, resulting in the engine becoming a steady if not spectacular seller despite its higher-than-average price.

However, there was a downside to all of this. Thanks to the influx of a number of British-made 1/2-A glow-plug models as well as the 0.8cc E.D Pep diesel at around the same time as the arrival of the A-S 55, the British marketplace was suddenly flooded with low-priced small engines. Moreover, this situation coincided with what may be seen in hindsight as the commencement of a steady decline in the demand for engines in general and small engines in particular among British modellers. As a result, the A-S 55 was launched into a shrinking market for small engines at the very time when that market was becoming saturated with low-cost domestic offerings. As events were to prove, the only long-term survivors of this period were the D-C Bantam glow-plug model and the long-established D-C Dart and Merlin diesels. All the others fell by the wayside, sadly including the A-S 55.

Although the engine remained on sale well into 1964, it's an odd fact that Allbon-Saunders appear to have made only desultory efforts to promote it. As far as we can ascertain, the company never placed a single advertisement in Model Aircraft. Presumably the fact that Aeromodeller enjoyed a wider circulation at the time made that magazine the best value for the advertising pound.

Even in Aeromodeller, advertisements appeared on a highly irregular basis. There were only three in the first half of 1960, the most serious promotional effort being a full-page advertisement in the April 1960 issue, clearly coordinated with the appearance of Ron Warring's test report. That advertisement was significant in that it confirmed that Allbon-Saunders had succeeded in bringing both E. Keil & Co. and Henry J. Nicholls Ltd. on board as distributors.

A further advertisement placed in the May issue of Aeromodeller made reference to Warring's very positive summation in his April test report. It appears that Allbon-Saunders may have correctly seen the appearance of Peter Chinn's equally laudatory report in the June 1960 issue of Model Aircraft as constituting the best possible form of advertising (and free at that!), making a separate advertisement by the company redundant in that month. However, it's a rather odd fact that following the appearance of the Model Aircraft test of the engine, no further adverts were placed in Aeromodeller until December 1960. That placement was clearly aimed at the Christmas rush. It included quotes from both Warring's and Chinn's test reports.

It's even stranger to have to report that the December 1960 Aeromodeller advertisement was the final advertising placement of them all! The engine continued to appear in dealer advertisements, but that was it as far as the company was concerned. The implication is either than the company expected the engine to sell itself through the spread of word regarding its qualities among users and their acquaintances, or that they already had their eye on other lines of business and no longer greatly cared about their model engine line.

The fact that the A-S 55 was most definitely built up to a standard placed it at a great disadvantage price-wise from the outset compared with such completing offerings as the D-C Bantam, which like most D-C engines by this stage was equally definitely built down to a price. The development of the A-S 55 took place in 1959 prior to the release of the Bantam. It must have come as quite a shock to Allbon-Saunders to find that they would have to compete in price terms with an engine which, while coming nowhere near to matching either the quality or performance of the A-S 55, sold for only �1 14s. 6d (�1.73).

It's greatly to Alan Allbon's credit that he clearly decided very early on that he was unwilling to join the race to the bottom which the Bantam had inaugurated. The quality of the A-S 55 was maintained, as was its price. The advertisements in May and December 1960 were both headed by the slogan "Quality Comes First", which was unmistakably Allbon's rallying cry against the Bantam and its ilk. Allbon clearly intended to find out whether or not British modellers were prepared to pay for quality and performance or whether price was all that mattered.

Sadly, it appears likely that Allbon-Saunders got the answer to this question very quickly, soon recognizing that their fine little creation stood a very poor chance of long-term survival in the cost-driven marketplace which had developed largely as a result of Davies-Charlton's aggressive cost-cutting at the expense of quality. Allbon and his colleagues were clearly not prepared to continue to engage in a marketplace in which quality was subordinate to price. It's very likely that it was at this early stage that the company abandoned its original ambitions regarding the expansion of its model engine range, instead seeking other outlets for its capabilities. This would explain both the early loss of advertising momentum and the relatively low production figures for their fine little unit.

It's clear in retrospect that the advent of the Bantam was in many ways a disaster for the British model engine industry, since it established price rather than quality or performance as the yardstick by which the average modeller judged an engine. Enough British modellers embraced this short-sighted philosophy to cause the British model engine industry to lose a number of very capable manufacturers, a situation which was hardly to the benefit of the modelling public in the longer term. Sadly, Allbon-Saunders was among them.

Even so, despite its price disadvantage as well as the seeming lack of attention to its promotion, the A-S 55 maintained a presence in the marketplace for some years, still selling in 1964 at a slightly reduced price of �2 11s 0d (�2.55 in today's money). This remained substantially more than the asking price of competing models such as the Bantam, but the A-S more than matched the Bantam for performance and was both sturdier and far better-made to boot. In addition, it was a diesel, a form of ignition to which large numbers of British modellers retained a strong allegiance at the time. However, this was not enough to save it in the long term, and the engine had disappeared from the market by the end of 1964.

At present, we can't present a credible estimate of overall production figures. The actual number could only be estimated by the assembly of a statistically-reliable sample of serial numbers, which we don't yet have. The highest confirmed serial number currently reported is 2383, the lowest being 175. This makes it fairly certain that the sequence started at engine number 1 and that at least 2500 examples were manufactured in total. We'd be most grateful to any reader(s) out there who are able to supply serial numbers which extend the presently-known range.

The fairest comment that can be made at present is that the engine appears to have been manufactured in relatively modest numbers by industry standards. It seems more than likely that from the outset Allbon-Saunders were involved in precision engineering in a broader sense and that the manufacture of model engines was very much a sideline. The engines may in fact have been made in a number of batches during down-time from other work. The number produced seems woefully insufficient to keep a manufacturing facility busy full-time over a four-year period.

However and whenever production took place, having sold a sufficient number of these fine little engines to make his point (if there was one to make), Allbon finally abandoned the model engine field altogether in 1964 and went instead into the optical industry. Sadly, this ended a sixteen-year involvement with the model engine trade which had throughout reflected great credit upon Alan Allbon's abilities. It also ended the four-and-a-half year presence of the A-S 55 in the British model engine marketplace.

It would seem that the Allbon-Saunders company was very successful in establishing itself in its new line of business, since the company remained in operation under that name until December 12th, 1996. On that date the company name was changed, most likely in conjunction with a change of ownership given the fact that Alan Allbon (presumably like Mr. Saunders) must have been at least into his seventies by that time. The successor company was (and is) named The Machining Centre Ltd., its stated business being precision engineering. This company remains in business today, still at the same location on Pembroke Lane, Milton.

One of the great pleasures of undertaking this research is the fact that it stimulates ongoing contact with valued friends and colleagues from around the world. Following the initial publication of this article, my good mate Jim Woodside was kind enough to contact me to confirm that his positive recollections of the two A-S 55 engines that he once owned were very much in step with my own assessment. Jim also recalled that some years ago a collection of tooling and "bits" from the old A-S model engine enterprise was put up for auction on eBay UK by none other than Mr. Saunders, who stated at the time that he was retiring and wished to pass this material along to someone having an interest. Jim has no knowledge of who may have acquired this material, but it would be of the greatest interest to learn what was included.

Conclusion

We've seen that the A-S 55 was manufactured in modest numbers over a 4-1/2 year period. In reality, the suggested production life may be considerably overstated, since it's actually quite likely that production had been undertaken in batches and that the final batch had been produced prior to 1964 as Allbon prepared to move into the optical industry. The engines sold during the final year at slightly reduced prices may very well have been New Old Stock being liquidated to recover capital.

In view of the general excellence of the engine, it's a matter for regret that this proved to be the sole model that was ever manufactured by Allbon-Saunders. Their initial advertisement of December 1959 had touted the A-S 55 as being the first of a "range of Diesel engines", a promise which was never fulfilled. We've noted the likelihood that sales of the A-S 55 suffered as a result of a combination of lower-priced competition from the likes of Davies-Charlton, E.D. and FROG coupled with what may be seen in hindsight as an already-shrinking market for model engines in general and smaller engines in particular. The consequent dampening effect on sales trends coupled with the increasing influence of price over quality seemingly led Allbon to begin looking elsewhere for his economic future quite soon after the introduction of the A-S 55. While one can well appreciate Allbon's motives for doing so, his decision was very much modelling's loss.

It's also a little surprising to find that although a reasonable number of these engines appear to have been sold, surviving examples in good original condition seem to be relatively thin on the ground today. Consequently, such examples as are offered for sale tend to be snapped up by collectors at surprisingly high prices, reflecting the effect of supply and demand. Presumably in their day these little engines were seen as very useable units which were run into the ground and then discarded as low-cost "throw-away" units either when they were worn out or when their owners had moved on to other things. It's the marginally useable and/or larger and more expensive engines that tend to survive unscathed ...

Having said all of this, good examples of the A-S 55 do appear on eBay and elsewhere on a fairly regular basis. Anyone acquiring an a example in good condition will be very well satisfied—these are really nice little engines which are sure to please any model diesel enthusiast!