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Locomotive Exchanges through the steam years. Swapping and learning the lessons. . . . . .

The GWR’s “Pendennis Castle” leaving Kings Cross station with a test train in 1925. Photo: Mike Peart’s collection.

The story begins in 1870 when two London & South Western Railway locomotives were loaned to the South Eastern Railway for two months. The purpose was to inform firebox design to get the best out of poor quality coal. Then in 1909, the London & North Western Railway swapped passenger locomotives with the Great Northern Railway with the focus on coal consumption. Over the next year, the Caledonian, North British, Great Western and London, Brighton & South Coast Railways’ locomotives all found themselves being tried on other companies’ lines to test superheating of boilers for greater steam production and coal and water consumption. Locomotive design and equipment benefited thereafter.

Freight locomotives were tested at the Glenfarg Trials on the North British Railway in 1921. A Great Western Railway (GWR) 2-8-0 locomotive was tested against a North British (NBR) 0-6-0 and a North Eastern Railway (NER) 0-8-0. The seven-mile Glenfarg Incline between Edinburgh and Perth had a gradient around 1 in 75. The GWR’s number 2804 pulled a 590 ton train up the incline successfully but had trouble later with a 686 ton train. Snow was falling at the time and this affected adhesion and blocked the gravity sanders. Hence the train stalled having been sabotaged by the weather. The NBR 0-6-0 successfully managed a 477 ton train and the NER T3 class 0-8-0 managed a 755 ton train albeit in fine weather in August!

Then there were the 1925 exchanges when the GWR’s “Castle” class exchanged with the LNER’s Gresley A3 Pacifics. Thus A3 “Victor Wild” did battle on Western metals down to Plymouth while “Pendennis Castle” astonished onlookers by taking a 16-coach train out of Kings Cross with ease and getting up to 83 mph at Arlesey. The LNER loco “Victor Wild” fared not quite as well although both companies claimed victory for their designs and quietly made improvements as a result. In 1926, another exchange saw the GWR’s “Launceston Castle” working out of Euston on the LMS main line whilst an LMS 4-4-0 Compound was seen on passenger services between Paddington and Bristol.

In May 1948, Robert A Riddles, the Railway Executive’s member for all mechanical and electrical engineering, started to preside over the major programme of locomotive exchanges that saw passenger, mixed traffic and freight locomotives from the pre-nationalisation companies being used on other companies’ lines. He wanted scientific evidence on the performance of the classes chosen for interchange in relation to performance, operating costs, maintenance, reliability and interchangeability. He was assisted by Roland Bond and Ernest (E S) Cox, both of whom he had worked with on the LMS where he had been vice-president. This team went on to lead the design of the new British Railways Standard locomotives. In 1943, Riddles had designed the War Department 2-8-0 class “Austerity” or “WD” locomotives. A total of 935 were built by the North British and Vulcan Foundry companies. 733 were later absorbed by British Railways along with 25 of the War Department 2-10-0 class locos built by North British.

“Coronation” class 46236 “City of Bradford” pictured at Crewe in 1961. Photo: Mike Peart.

Apart from providing vital evidence for engineers, the 1948 Locomotive Exchanges delighted trainspotters and enthusiasts. One day, the 8.30 a.m. Plymouth to Paddington train was hauled by LMS “Coronation” class 46236 “City of Bradford”. Ten days earlier the locomotive had been on the Kings Cross to Leeds run. Then the same train on different days was hauled by LNER A4 class 60033 “Seagull" and 60022 “Mallard” (which failed near Newbury). During the period of the exchanges, Western Region spotters would also have seen the LMS “Royal Scot” 46162 “Queen’s Westminster Rifleman”; the SR “Merchant Navy” 35017 “Belgian Marine”; the LMS “Black Five” number 45253; the LNER “B1” number 61251 “Oliver Bury” and the SR “West Country” number 34006 “Bude”. The GWR’s “Modified Hall” 6990 “Witherslack Hall” worked the 10.00 a.m. Marylebone to Manchester express. LMS “Black Five” number 45253 and SR “West Country” number 34006 “Bude” were also tested on this route.

As a result of testing and lessons learnt, the Southern Railway’s “Merchant Navy” class were rebuilt. This is “Belgian Marine” in its rebuilt form at Southampton in 1961. Photo: Mike Peart.

On freight train tests, the contenders were LNER “O4” 2-8-0 number 63773; the LMS “8F” 2-8-0 number 48189; the WD “Austerity” 2-8-0 77000 and the WD “Austerity” 2-10-0 numbered 73774. The GWR 2-8-0 3803 also took part running between Acton, Stoke Gifford and Severn Tunnel Junction with loads varying between 600 to 1,108 tons. Freight trains of similar tonnages were tried between Eastleigh and Bristol via Trowbridge and Bath. Various measures were tested – coal and water consumption and quality (measured in summer and winter), maximum horsepower outputs, handling, adhesion and slipping. Yorkshire hard coal from South Kirkby and Nottinghamshire coal from Blidworth was provided as standard for the trials. The results informed the design of the last of British Railways’ Standard classes around 50 of which are preserved as static or working examples.

Mike Peart

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09. 3. 2023

The Gresley locos in the 1925 trials were class A1, not A3. The first A3 ("super-Pacific") was Felstead in 1928.

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