Mainline steam trains in Great Britain
The most famous steam locomotive operating on the British main line is the 1923 built "Flying Scotsman". After being taken into public ownership in 2004, following a decade long refit it returned to mainline service in 2016. The fastest steam locomotive ever built, the 1938 built "Mallard", was also certified for main line operation briefly in the 1980s.
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.