LMS Route: Rugby to Tamworth

Trent Valley Lineside - Cathiron: lnwr_cath1142

Ex-Southern Railways 4-6-2 Merchant Navy class No 35017 'Belgian Marine' is seen coupled to an ex-LMS tender during the locomotive exchanges on 21st May 1948. The Southern Railway had no water troughs due to their adopting electrification through the use of a third rail. Therefore whilst on test No 35017 was given an ex-LMS tender to facilitate water pickup during the locomotive exchanges. Behind the tender can be seen a dynamometer car which recorded the performance of the locomotive under varying conditions - obtaining information relating to speed, acceleration, superheater and smokebox temperatures. Apparatus contained in the car was activated by an extra wheel which was lowered into contact with the rail when tests were to be made.

Designed by Oliver Bulleid and built at Eastliegh works as Southern Railways No 21C17 in April 1945 the Merchant Navy design was unusual in many ways. Bulleid advocated a continental style of locomotive numbering, based upon his experiences at the French branch of Westinghouse Electric before the First World War, and those of his tenure in the rail operating department during that conflict. The Southern Railway numbers followed an adaptation of the UIC classification system where "2" and "1" refer to the number of unpowered leading and trailing axles respectively, and "C" refers to the number of driving axles – in this case three. All the locomotives of Pacific wheel arrangement therefore carried the prefix 21C, followed by the number in the group.

They were also known as Bulleid Pacifics, Spam Cans or Packets. Incorporating a number of new developments in British steam locomotive technology, the design was among the first to use welding in the construction process; this enabled easier fabrication of components during the austerity of the war and post-war economies. The locomotives featured thermic syphons and Bulleid's innovative, but controversial, chain-driven valve gear. The class members were named after the Merchant Navy shipping lines involved in the Battle of the Atlantic, and latterly those which used Southampton Docks, an astute publicity masterstroke by the Southern Railway, which operated Southampton Docks during the period.

Renumbered by British Railways as No 35017 to fall in to line with the other region's method of numbering, N0 35017 was later rebuilt in March 1957 to a more conventional design and look with the boiler cladding removed and the provision of orthodox valve gear. It retained both the boiler - acknowledged as being superb for steam raising - and the unusual Bulleid-Firth-Brown wheels, which were lighter, yet stronger than the spoked equivalent and in this form was withdrawn in July 1966 from Weymouth shed being scrapped in September 1966 by J Buttigieg of Newport.

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