 He was not able to proceed with his plan due to the Second World War but did try out some of his ideas by rebuilding Nigel Gresley's P2 class 2-8-2 as A2/2 pacifics and building the last four V2 class already on order as A2/1 pacifics.At last in April 1944 Thompson received authority to build thirty new locomotives of his A2 type during 1945, and a further thirteen during 1946.The basic design of the locomotive was similar to the A2/2 rebuilds in terms of the frames, boiler and motion, but boiler pressure was increased to and the cylinder diameter was reduced to .