Early post-war production totals and engine numbers are published elsewhere but it seems that popular sources for this information are not accurate. Peter Gallagher in Australia, long time Triumph expert, has spent many years unearthing the facts and is, in his words, 'nearly there'. His research has been broad: based on factory records, contemporary accounts, consultation with surviving Triumph people, as well as examination of examples of number stamping styles. As with any correct research procedure, he accepts degrees of likelihood, as opposed to certainty. In other words, these results are very much closer, indeed probably correct, but always subject to modification if good evidence emerges of detail changes. For that reason we would always like to hear of examples of machines that challenge any of these totals.
Post-war production took about five years to reach the well-ordered, matching numbers system in 1950. Therefore, at the end of the war the process starts in a fairly confused way, with firm evidence now emerged that some existing pre-war TF frames were adapted for the first of the post-war production. The 1945 season seems to have consisted only of 5T Speed Twin models. Engine numbers used a 45 prefix followed by the model & engine number eg 45 5T 72250.
Pre-war frame numbers apparently ran to TF 4313 (5T engine). However, some of the first post-war 5Ts showed lower/earlier frame numbers so production is not entirely chronological and there is an overlap. There are examples of post-war bikes with frame numbers preceding 4313 and the majority seem to be in the TF 4200/4300 range. Presumably these frames were salvaged from the ruins of the factory having survived as more robust items. They were then modified with the lower front down-tube engine mount and dynamo 'dent'. These '45 bikes with pre-war frames were still number-stamped in the pre-war position, ie across the top of the steering head, and again at the top, rear of the saddle tube, confirming that the frames were pre-war survivors.
Once these early frames were used up, the post-war frame numbering started from TF 5001, stamped in the new position down the left side top of the down-tube. Engine numbers (as recorded in the engine order despatch book) for 1945 5Ts ran from 72001 - 72229. However, engine '46 5T 72217 has recently come to light, indicating that the change to the 1946 year prefix was introduced during this sequence. Making 45 prefixed models even scarcer with a possible maximum of only 216 models. Of these, approximately half used modified pre-war frames.
Other significant aspects of this (1945) seasons 5T models are the late (October - December) production dates, timing that would normally have put them firmly into the next season. In addition, there is evidence that some were finished in black. Indeed, there is more evidence of black survivors than those in amaranth red.
As mentioned above, the last quarter of the years production would normally fall into the following years (seasons) models. This seems to stem from production switching to the new model following the annual works holiday at the end of July/beginning of August. As a result, the next seasons models tended to emerge by September. This would also fall into line with the annual Earls Court show, usually in October, as with pre-war production. By the time the show came around, hundreds of the new models would be ready for display and sale. However, production at Triumph was never entirely regimented, especially in these early post-war years, and it is always possible to find anomalies as old stock is used up, and occasionally suppliers are slow. In addition, there is clear evidence of mistakes in date stamps on engines. Examples have been identified of engine numbers that correspond well to an existing sequence but perhaps just one number is missing on an original machine that is clearly genuine. In addition, there are sometimes errors in log books or other records. These mistakes can only be assumed if there is good evidence of an otherwise genuine machine or entry, but it does serve as a warning.
In addition, there is an element of common sense. If, for example a numbering anomaly is claimed on a bike that has been in circulation for a while and has had much work done, together with a clear benefit in value, then the claim needs to be treated with scepticism. If, however an original component with a watertight provenance is unearthed with an odd number that would only confuse later, then we can accept that much more readily.
Because of the embedded date code, the engine number is listed in the engine order despatch books in chronological order, enabling identification of each machine. It is therefore the engine number which denotes the model year where batches are assembled with frame numbers that may not always run at the same rate.
For 1946 the same format, a two number (46) prefix was used. Engine numbers ran on from the previous season, starting with 72230. The range now expanding to three models: 5T Speed Twin, Tiger 100, and a new 350cc 3T in a different frame with a new frame number prefix TC, starting at TC 101. The engine number sequence for 1946 ran to 79546 in the summer, suggesting a much more businesslike total of 7316. It seems that 3T production had started in November 1945, but unlike the 5T models, were stamped as '46 right from the start.
The 1947 season engine numbers start at 79547 ( a model 3T) and run through to 89332 (model 5T) which shows a run of 9785 machines. Again the engine number prefix is two digits (47)
This continues for 1948 for the great majority, starting with 48 3T 89333. However, towards the end of the season the prefix changes to a single year digit (8) appearing at the front of the engine number with no space between. Numbers went to 5T 8102250. Indicating a run of 12917 machines.
For 1949 the new format continued, ie, the year code 9 appeared at the front of the engine number with no space, resulting in the apparent seven digit number. It begins at T100 9102251 and finishes with 5T 9113386.
As mentioned at the beginning, for 1950 a more regimented approach to final assembly and record-keeping was adopted. Engines were fitted into the next bike on the assembly line and at the end of the line, prior to the petrol tank being fitted, the frame number was stamped to match the number on the engine. This resulted in the newly painted frame having the stamping “break” the paintwork which is why original paint bikes can show rust in that area. From 1950 the factory records were in the form of Engine Build books, Frame Build books and Dispatch books. This, together with the new matching numbers system allows a clearer demarcation line between the model years.
Thanks for permission, and full credit to Peter Gallagher for all the above info.