LNER class A4 is a class of streamlined 4-6-2 pacific type locomotives designed by Sir Nigel Gresley for the London and North Eastern Railway in 1935. Their streamlined design gave them high-speed capability as well as making them instantly recognisable and one of the class, 4468 Mallard, holds the world record as the fastest steam locomotive. Thirty-five of the class were built to haul express passenger trains on the East Coast Main Line from London (Kings Cross) via York and Newcastle to Edinburgh. The locomotives remained in service on the East Coast route until the early 1960s when they were replaced by the powerful Deltic diesel locomotives. Several A4s continued to work in Scotland, particularly on Aberdeen - Glasgow express trains, for which they were used to reduce the timing to 3 hours, and over the Waverley route between Carlisle and Edinburgh. It is quite fitting that the reopening of the Waverley route as far as Tweedbank was perfomed by Her Majesty The Queen and a train hauled by preserved A4 class locomotive 60009 Union of South Africa.
Lieutenant-Colonel Sir Murrough John Wilson KBE (1875-1946) was a British Army officer, MP for Richmond Yorks (1918-1929) and member and of the railway executive. A director of the North Eastern Railway from 1912 and the combined LNER. Locomotive 4499 was renamed Sir Murrough Wilson in April 1939, likely marking Sir Murroughs' retirement as director of the LNER to join the wartime railways executive which had been reformed in September 1938.