Thompson Pacifics of the LNER

When Edward Thompson was appointed Chief Mechanical Engineer of the London and North Eastern Railway in April 1941, he envisaged a new standardisation programme involving ten locomotive designs including two Pacific types. These were an express passenger type (designated A1) with 6 ft 8 in (2.032 m) driving wheels and a ‘heavy passenger and freight’ type (designated A2) with 6 ft 2 in (1.880 m) driving wheels. 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
Thompson drew up two modified 3-cylinder designs both of which discarded the Gresley conjugated valve gear and had separate sets of Walschaerts valve gear for each cylinder. Due to space restrictions, the middle cylinder could not be parallel with the outside cylinders. One design had the middle cylinder forward of the outside cylinders, whilst the chosen design had the middle cylinder further back. Both designs used A4 boilers. A new set of frames was built for the rebuild. These were similar to A4 frames except for the wheel spacings at the front. Thus very little of the original locomotive was retained. The resulting wheelbase was 38 ft 5 in (11.709 m), even longer than the Gresley P2s
No. 4470 Great Northern (the very first Gresley Pacific) was chosen for this rebuilding, rather than being retained for future preservation. There has been much debate on the reason for this choice. Some state it as bad luck, whilst others clearly blame Thompson for letting his personal feelings towards Gresley cloud his judgement. O. S. Nock describes it as ‘the most disappointing and tactless act in his short and stormy career as CME,’ and Allen stated ‘he turned it into a machine of such hideous appearance as might well have made its designer turn in his grave.’ It is known that the Chief Draughtsman and a number of high up officials within the LNER unsuccessfully tried to deter Thompson from rebuilding this particular engine. The rebuilt locomotive appeared in traffic in September 1945 and was classified A1 and the remaining sixteen locomotives of Gresley’s A1 class were re-classified A10. Originally, the plan was to rebuild all of these to the new design but this never occurred. There were also plans for streamlining all the members of the new A1 class, but these were never acted upon (from Wiki)
I have added 7 new photos of 4470/113/60113 Great Northern
60113 Great Northern at Peterborough North c1958
https://tinyurl.com/yxug2uxm
with different numbers
4470 Great Northern
https://tinyurl.com/y2kc99c4
113 Great Northern
https://tinyurl.com/y6z45t24
60113 Great Northern
https://tinyurl.com/y4po3yoj

Neil