I doubt it was specifically to do with Spitfires. In 1937 the UK Defence Budget was about 2.7% of GDP despite serious concern about the high risk of war with Germany, Italy and Japan, but also with Soviet Russia due their aggression in Finland. Defence had been underfunded since the end of the Great War and Britain's armed forces weren't ready for a major conflict.

In 1938 the government pressed the panic button and tripled the Defence Budget to 9% of GDP. It might be possible to link the contract number with the Staff Requirement by researching the National Archives. But I think that might be misleading. By 1940 we were at war and the lathe could have been sent almost anywhere it was needed.

The 1938 expansion went far beyond any single aircraft. The lathe might have been bought to service Spitfires, but more likely it met other needs. This included ground engineering at multiple new airfields as well as direct support of aircraft, and not just the planes going into service in 1938, but planes planned to be in service by 1945.

As we know, Adolf went a step too far in 1939. During the phony war defence spending rose to 40% of GDP, but it was too late to deal with the already well-prepared Germans. It wasn't until mid-1943 that the British developed sufficient force to really hurt Germany. Of defence procurement Churchill said: 'In year 1, nothing. In year 2 a trickle. In year 3 a flood.'

If only we had some political way of defusing the tensions that cause European Wars…

Dave