LNER Class A4
The Class A4 is a class of streamlined 4-6-2 steam locomotive designed by 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 route from London Kings Cross via York to Newcastle, and later via Newcastle to Edinburgh, Scotland. They remained in service on the East Coast Main Line until the early 1960s when they were replaced by Deltic diesel locomotives. Several A4s saw out their remaining days until 1966 in Scotland, particularly on the Aberdeen - Glasgow express trains, for which they were used to improve the timing from 3.5 to 3 hours.
British Rail Class 91
A Class 91, 91010 (now 91110) holds the British locomotive speed record at , set on 17 September 1989, just south of Little Bytham on a test run down Stoke Bank with the DVT leading. Although Class 370s, Class 373s, and Class 374s have run faster, all are EMUs, which means that the "Electra" is officially the fastest locomotive in Britain. Another loco (91031, now 91131), hauling five Mk4s and a DVT on a test run, ran between London King's Cross and in 3 hours, 29 minutes and 30 seconds on 26 September 1991. This is still the current record. The set covered the route in an average speed of , and reached the full several times during the run.