The London and North Eastern Railway (LNER) Edinburgh to Aberdeen route had steep gradients and tight curves and the express passenger service was usually worked by a double header of two small engines. To overcome this situation, HN (later Sir Nigel) Gresley, Chief Mechanical Engineer (CME) of the LNER began designing a new locomotive at the LNER Doncaster Works in 1932. The 2-8-2 configured locomotive was given the classification P2 and had four driving axles for greater adhesion, an A3 type boiler (albeit with a 50 sq ft grate) and a Kylchap double blastpipe/chimney. A total of six of the Class were built.

As the first two were returned to Doncaster for overhaul, they were fitted with streamlined fronts similar to the A4 Pacifics. The last four to be built were outshopped with streamlined fronts. By the end of 1944 the whole Class had been rebuilt by Gresley’s successor as Thompson class A2/2s. ‘The A1 Steam Locomotive Trust', builders of the A1 locomotive 'Tornado', are currently in the process of building a continuation of the P2 class; 2007 ‘Prince of Wales’. Whilst this locomotive will be based on the design of 2001 ‘Cock o’ the North’, 2007 will incorporate some changes such as sharing a boiler design with A1 ‘Tornado’ and incorporating an improved pony truck design.