The class was designed at Derby Works and introduced in 1953. The design derived from the LMS Ivatt Class 2 2-6-2T which BR had built after nationalisation. Modifications were made to the Ivatt design including a reduced cab to reduce the loading gauge and some standard fittings. BR classified them 2MT, emphasising a mixed-traffic role.

As most services which required 2MT 2-6-2Ts were already served by the 130 Ivatt engines, B.R. only ordered 30 engines, which eliminated pre-grouping steam locomotives as much as possible on local services.

None of the class survived the cutter's torch. However, four BR Standard Class 2 2-6-0 locomotives did survive, and one of these, 78059, is being rebuilt into 2-6-2T "84030". This takes the next number in the original series. 78059 was chosen primarily because it lost its tender. Further reasons cited by the Bluebell Railway, where 78059 is based, are the suitability of the locomotive class for the railway's service trains, and because the tender version of the class was never allocated to the Southern Region, and hence the tank version (which was allocated there) is far more appropriate for the Bluebell's Southern Region location.

As of 2013, 78059 was considered to no longer exist, as the fitting of the hind engine frame extensions have turned it into 84030.