I have now made two previous posts on this blog about the 1948 locomotive exchange trials, and my models of the locomotives that featured on Southern metals and would have passed through Salisbury and therefore can occasionally be seen on Fisherton Sarum. The first Talking Stock # 2 post focused mainly on  the Express Passenger and general purpose locomotive trials whilst the second post Talking Stock #30 focused on the less often referred to freight locomotives trialed. This post is by way of my own thoughts and conclusion about the actual trials themselves.

These trials were not attempting to judge an overall winner but to gain an insight and comparisons of good design and practice that could be in theory carried across into the future design of new British Railways steam locomotives.

A number of observers are of the opinion that the trials should have been larger to encompass more locomotive varieties and that there are some notable missing classes.

Some of the missing classes that have been mentioned include: the Western Region’s Castle Class, the London Midland Region’s Royal Scots or Jubilees, the Eastern Region’s V2s and of course the Southern Region’s Lord Nelson; of which a direct comparison with the Royal Scot Class would have been very interesting due to similarity on the origins of the designs. Also as I mentioned in my Talking Stock #30 post the Southern did not put any freight locomotive forward so perhaps the design of the S15 whilst being a possible contender was considered to be too old.

One major inconsistency that directly affected all the recorded parameters, despite all the precautions taken, was with the locomotive crews. The method of engine control varied; from those crews trying to be as economic as possible, such as the London Midland crews, whom allowed timings to slip to the benefit of coal consumption; whilst others, especially the Southern Region crews,  were keen to show the best of what the engines could do performance wise including some extremely impressive hill climbs. Coal and water, but not oil, consumption’s were all recorded and compared along with horsepower outputs and overall efficiencies. These therefore varied considerably by the style of driving. Additionally; loads on each test run varied rather than being controlled to be something near constant and that on a number runs considerable signal checks were experienced rather than Control ensuring a clear run where possible.

Also the Southern Region crews were not used to such prolonged running due to the relatively short maximum length of route available; 143 miles, between Waterloo and Exeter compared to runs on other regions ranging from 172 to 299 miles. The later being between Euston and Carlisle which was also longer than usually worked by the Eastern Region crews too.

As all locomotives were coaled with Yorkshire hard coal this immediately put the Western Region engines at a slight disadvantage as the drafting arrangements for these engines had been designed around the use of softer South Wales steam coal. Subsequent additional tests were carried on the Western Region with these engines on their more usual South Wales steam coal which did result in an improvement in coal consumption.

Due to the inconsistencies explained above it is very difficult to grade or score the performances of individual locomotives designs. In some cases locomotives were inconsistent on consumption, horsepower between runs or varied from route to route.  Some of the possible conclusions that can be drawn are as follows:

• In the express passenger group it was a close run thing on efficiencies between the Eastern A4s and the London Midland Duchess Class.
  All of the Pacific’s were very consistent across all runs; however the results of the 4-6-0s varied more across the different routes.
• In the general purpose engines group the Southern Region West County Pacific’s put in some brilliant and very impressive performances but these were at the expense of efficiency figures as already implied. The London Midland Region Class 5’s showed the best efficiencies of this group. The Eastern Region B1 class showed some considerable fluctuations in efficiencies between routes.
• The greatest variation in overall efficiencies was experienced with the freight group with no engine type being consistent across all routes although the closest to this was the Eastern Region O1 class, but it put in a variable performance on the Eastleigh – Bristol route for an unexplained reason.
• The widest variation of all in efficiencies and performance was seen with the Ministry of Supply WD 2-8-0 and 2-10-0 locomotives. In fact the 2-8-0s did not on the whole distinguish themselves very well at all.
• Whilst the Eastern Region A4 class locomotives put in some fine performances they were marred by the fact that there were three failures during the testing attributed to the middle big end overheating on each occasion.

The data recorded and utilised in the final report was not generally seen by most as being fully conclusive, not helped by the fact that it took no account of the costs of construction or average costs of maintenance for each locomotive design.

Whilst it is also generally considered that future British Railways standard designs perhaps bore more resemblance to the origins of their designer, the trials were if nothing else a Public relations exercise for the newly formed British Railways as a show of unity between the now Regions.