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.
High-speed rail in the United Kingdom
Various claims exist for the first locomotive to break the barrier, notably the Great Western Railway's "City of Truro" (1904) and the LNER's "Flying Scotsman" (1934). Locomotive power capable of reaching has existed in Britain since 1938, when the LNER's "Mallard" broke the steam locomotive speed record.