LMS Ivatt class 2 2-6-0
Elderly 0-6-0s formed the backbone of the low-powered locomotives within the LMS fleet. William Stanier had concentrated on introducing larger engines and it was left to George Ivatt to introduce a new class of low-powered locomotive. He designed a tender version of the Ivatt Class 2 2-6-2T, introduced at the same time, which was inspired by the Stanier Class 3 2-6-2T, which was inspired by the Fowler Class 3 2-6-2T. The 2-6-0s had greater range: 3,000 imperial gallons (14,000 l; 3,600 US gal) of water and 4 long tons (4.1 t; 4.5 short tons) of coal compared to the tank design's 1,350 imperial gallons (6,100 l; 1,620 US gal) and 3 long tons (3.05 t; 3.36 short tons). So they were well-suited to their task and, following attention to draughting problems by both Derby and Swindon, quickly became a success. Further engines of this type were built as the BR standard class 2 2-6-0, these locomotives having BR standard fittings and a modified cab and tender profile to allow completely unrestricted route availability; both LMS and BR 2MT moguls are often nicknamed "Mickey Mouse".
A total of 128 were built between 1946 and 1953, mostly at Crewe. 20 were built by LMS and given the numbers 6400–19. On nationalisation in 1948 40000 was added to their numbers to become 46400–19. The remaining 108 locomotives of the class, numbered 46420–46527 were built by British Railways, and from 46465 (Darlington, 1951) an increase in cylinder diameter of 1⁄2 inch (13 mm) yielded a tractive effort of 18,510 lb (8,400 kg), 1,100 lb (500 kg) greater than the original design. The LMS classified them 2F, BR as 2MT.

LMS Ivatt class 2 2-6-2
The LMS had various elderly tank engines and the operating department required a new small class 2 locomotive to replace them. Noting that the Great Western Railway 4500 and 4575 Classes of 2-6-2T ('Prairie') had been successful, George Ivatt designed the new engine type incorporating self-emptying ashpans and rocking grates which were labour-saving devices. A tender version, the Ivatt Class 2 2-6-0 was also produced. The LMS classified them as 2P, but BR preferred the classification 2MT.
The class was introduced between 1946 and 1952. They were based on the LMS Stanier 2-6-2T which was, in turn, based on the LMS Fowler 2-6-2T. Ten were built by the LMS before nationalisation in 1948, and were numbered 1200–1209. British Railways added the prefix '4' to their numbers so they became 41200–41209. A further 120 were built by BR, numbers 41210–41329. Most were built at Crewe, including 41272 — the 7000th locomotive to be built there, but the last ten were built at Derby. Fifty engines were fitted with push-pull equipment, these being Nos. 41210–41229, 41270–41289 and 41320–41329.