The 3MT 2-6-2s were likely conceived to replace medium powered tank engines like the GWR 45xx small prairies which were approaching the end of their economic working lives by the 1950s and provide a larger engine than the 2MTs which had replaced many more elderly types on the LMS and SR. The GWR No.2 boiler was used on the GWR 5101 and 61xx class large prairies, class 4 engines, so was more than capable of delivering the steam needed by the 3MT.
Allocated to the Western, Southern, North Eastern and Midland regions the engines should have been revolutionary, but were to have a short lives under the modernisation programme. By the late 1950s DMUs were replacing steam-hauled trains on branch and local passenger services and diesels of type 1 were specifically intended for the kind of light goods services operated by small steam engines. The longest lived was 82019 at 14 years 10 months, roughly equating to the time a second heavy overhaul would be due.
Sadly none of the class were lucky enough to be stored at Woodhams yard in Barry so no original engine has survived to preservation, though the class would have been ideal for todays' heritage railways. A project to build a new locomotive, to be number 82045, is progressing steadily at the Severn Valley Railway, the chassis now approaching completion and boiler construction has commenced.
As historic preserved engines wear out and require more work to restore 82045 may prove the first of a new class of 3MT tanks.