The duchess class steam locomotives were the most powerful and the fastest steam trains of all time. In 1938 the mallard set the speed record of 126 mph although it damaged the boiler doing so. These trains looked more modern than their years because they were streamlined and indeed were as fast as modern trains. During the second world war trains were limited to 60mph due to the shortage of coal and during the blackouts the only lighting allowed was the stop and go lights for the trains although this wasn’t very bright. Only two duchess class trains survive to this day. One is the city of birmingham which is in the thinktank which was the science museum. I have been there and they fire the engine up several times a day and it is very impressive. In 1968 the steam trains in the UK ceased to run on the train network although they still do on historic lines like the severn valley railway. On special occasions the flying scotsman runs on the svr line as well as other special trains. The flying scotsman was among the fastest steam trains.
