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.
Steam turbine locomotive
In May 1954 Baldwin built a steam turbine-electric locomotive for freight service on the Norfolk and Western Railway (N&W), nicknamed the "Jawn Henry" after the legend of John Henry, a rock driller who famously raced against a steam drill and won, only to die immediately after. Length including tender was 161 ft 1-1/2 inches, probably the record for a steam locomotive; engine-only length was 111 ft 7-1/2 inches, perhaps the record for any single unit.