It’s a modern International strategy
Find areas with development grants (or tax rebates) etc
Get local financial help to build it
Use new location to squeeze expensive labour costs in another country by threatening to move production
Dont worry if only have one contract, the expensive machine tools, jigs, jacks etc can be unbolted from floor and moved elsewhere if needed.
Scottish Labour is cheap, and places like Rosyth should mean skilled labour available. Also Longannet already has ship access.
Chesterfield is close enough to poach (or get staff already surplus) from Derby.
Simple Strategy which makes easy profit, not done because UK is fun place to build trains