LNER Thompson Class A1/1

The LNER Class A1/1 was a single 4-6-2 Pacific express passenger locomotive, rebuilt in 1945 by Edward Thompson from Nigel Gresley's original Class A1 locomotive No. 4470 Great Northern. Thompson meant it as the prototype of a new design improving on the Gresley A4, with divided drive on the centre cylinder, three independent sets of Walschaerts valve gear instead of Gresley's conjugated gear, and a diagram 107 boiler from the A4 on A4 frames. Very little of the original engine survived the rebuild, and the choice of the first Gresley Pacific drew lasting criticism. It was among the most powerful LNER Pacifics, with a tractive effort of 37,400 lbf. Sixteen new engines ordered in 1945 were deferred when Thompson retired and were built in 1948 as the Peppercorn A1 design. Renumbered 60113 under British Railways, it was withdrawn on 19 November 1962 and broken up at Doncaster Works.