The London and North Eastern Railway (LNER) produced several classes of locomotive, mostly to the designs of Nigel Gresley, characterised by a three-cylinder layout with a parallel boiler and round-topped firebox. It produced the most famous locomotive of its day, 4468 'Mallard', the holder of the world steam locomotive speed record. It also built the world-famous 4472 'Flying Scotsman'. However, its locomotive inheritance was much greater than just the 'A4 Class', it also produced highly successful mixed-traffic and freight designs.