 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 July 1944 Thompson began work on designing his new A1 class which would be an improved version of the A4 class.However before building any new locomotives he decided to rebuild one of the surviving Gresley pacifics of the A1 class to try out the new design.