GNR Class H4

The Great Northern Railway Class H4, classified K3 by the London and North Eastern Railway, was a class of 2-6-0 steam locomotives designed for mixed-traffic work and was a more powerful development of the earlier H3 class. Its 6-foot-diameter boilers were the largest fitted to any British locomotive up to that date. The first ten were built at the GNR's Doncaster Works in 1920 to Nigel Gresley's design. After the grouping the type became an LNER standard, and six further batches came from Doncaster and Darlington Works, Armstrong Whitworth, Robert Stephenson and Company and the North British Locomotive Company, the last of 193 examples being delivered in 1937. Crews nicknamed them Jazzers after their exhaust beat and unbalanced gyratory movement. All were withdrawn and scrapped between 1959 and 1962.