The A2s were a rather muddled class, made up of rebuilt locomotives and 'new builds'. It incorporated Edward Thompson's rebuilds of Gresley's six Class P2s (A2/2s) and four were a development of the A2/2 but with V2 boilers (A2/1s).

It also included 15 new locomotives built by Thompson (A2/3s) and 15 more built from 1947 (A2s) by AH Peppercorn, who succeeded Thompson as CME. Peppercorn's 15 engines were based on Thompson's A2/2 but were almost 2 feet shorter. They started to arrive in 1947 and only two carried LNER livery.

Our model is of the last Pacific locomotive built by the LNER and was the first of Peppercorn's shortened design. The rest were built by British Railway and a further 20 engines had been ordered but subsequently the order was cancelled. No.525 later appropriately received the name A.H.Peppercorn. While the first two were released in LNER livery, the rest appeared in Apple green with 'British Railways' on their tenders. From 1949 they were repainted in BR Brunswick green.