So that would have been just before the first A1s were launched. A slightly earlier Gresley pacific design iteration that had not been built perhaps? Would surely have been a 3-cylinder design as the classic Gresley front end with conjugated valve gear was already fully developed by then, so the Crewe rebuild must have been a significant reconfiguration of the front end as well as the firebox.
From A1-like prototype to 5MT a mere 'rebuild'? I'm not buying it
Exactly - that's why it was done at Crewe rather than locally - see my earlier post.
Regarding being a Gresley A1 prototype, that's what Gordon actually was - an experimental prototype. He was used only for test runs and never entered regular service or given a GNR number. After being used to iron out any defects, when the production locomotives began to be built Gordon was deemed surplus to requirements and sold to the North Western Railway on Sodor in 1923.
The book is short on detail about Henry. To quote in full: '...rumours of a scandal at Doncaster in 1919 or thereabouts, about the theft of some drawings. Nothing was proved, but it was alleged that a Locomotive Builder with a grudge against Gresley had engineered a 'leak' so as to steal a march on him. His spy, however, blundered and took the wrong drawings. The mistake was discovered too late. The locomotive when built, showed so many faults that the builder was glad of a chance to unload his 'white elephant' on to a desperate customer.'
I interpret that as someone wished to steal drawings of Gresley's proposed A1 in about 1919 (presumably they would have been of Gordon) but by mistake some other drawings were taken and the locomotive built according to them turned out to be Henry.
There was a shortage of locomotives on Sodor in the 1920s and it appears Topham Hatt slipped up in that he thought he had bought an Atlantic from this unspecified builder, but instead was sent Henry. Being so short of motive power at the time Hatt just had to make do with anything he could get.
