Nigel Gresley
Sir Herbert Nigel Gresley (19 June 1876 – 5 April 1941) was an English railway engineer. He was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer (CME) of the London and North Eastern Railway (LNER). He was the designer of some of the most famous steam locomotives in Britain, including the LNER Class A1 and LNER Class A4 4-6-2 Pacific engines. An A1 Pacific, "Flying Scotsman", was the first steam locomotive officially recorded over 100 mph in passenger service, and an A4, number 4468 "Mallard", still holds the record for being the fastest steam locomotive in the world (126 mph).
Metropolitan Railway electric locomotives
The second ten, also constructed by Metropolitan Amalgamated, were built to a box car design with British Thompson Houston control equipment. These locomotives weighed 47 tons, and were long over buffers and entered service in 1907. The control equipment was replaced with the Westinghouse type in 1919.
In the early 1920s, the Metropolitan placed an order with Metropolitan-Vickers of Barrow-in-Furness for rebuilding the twenty electric locomotives. When work started on the first locomotive, it was found to be impractical and uneconomical and the order was changed to building completely new locomotives using some equipment recovered from the originals. The new locomotives were built in 1922-1923 and weighing 61½ tons, they had four motors, giving a one-hour rating of and a top speed of .