They were designed by The Met's Locomotive & Chief Electrical Engineer, Charles Jones. Delivered between October 1920 and June 1921, they allowed for the retirement of a like number of 0-4-4TC Class and 2-4-0TD Class locomotives. The H Class were considered to be good engines well-suited to the express trains they worked, allowing for a reduction in running times of up to six minutes. They were designed with a hauling capacity of 250 long tons (250 t; 280 short tons) and could negotiate curves of 300 feet (91 m) radius.
When the steam-hauled services were transferred from London Transport to the London and North Eastern Railway in 1937, all eight H Class locomotives were included to continue working the same trains. The LNER numbered them 6415–6422 and classified them as H2 Class. In the 1940s, they were moved from Neasden (LNER) shed to the Nottingham area and worked over other parts of the former Great Central Railway system.