In article , notvalidpmscott@btinternet
com (Paul Scott) wrote:

"tim....." wrote in message
...

Ah, this little bit of underground history was not known to me.
This explains why so much of this 'new' line was opened so
quickly. It was just converted from an overground railway
that was already there.

Its also helps explain why there appear to be far more
'underground' lines north of the river. It suited the mainline
railways to have certain commuter routes transferred to LT as
extensions of their routes - many of the current lines are the
result of transfers from the 'mainline' railways...

More the other way round, though. The Southern preferred to electrify its
network between the wars than to transfer it to the Underground, to the
extent that it was willing to build the Wimbledon-Sutton line in the
1920s and 30s rather than have the District extended to Sutton.

The Northern to Mill Hill East and High Barnet and the Central extensions
West of Ealing and East of Liverpool St are the main tube takeovers of
main line railways in the post-grouping era. The Bakerloo to Watford
Junction (to some extent as the main line usage always remained), the
Central to Ealing, the Northern to Edgware and the Piccadilly to
Cockfosters were all earlier new lines.

--
Colin Rosenstiel