In message , Tom
Anderson writes

Does anyone know if there was a route plan for the central stretch?
Would it just have slavishly followed the Northern line, or might we
have seen, eg, a Stockwell - Vauxhall - Piccadilly Circus - Goodge
Street sort of alignment?

As I recall (but I could be wrong), the plan was to follow the original
route fairly exactly, because in those days deviations would have meant
tunnelling under vast numbers of privately-owned properties, the owners
of which would have required compensation under wayleaves legislation.
--
Paul Terry