In article , Michael Hoffman
writes
John wrote:
It is a very good read and does suggest reasons for
the lack of tube south of the Thames.

Care to share?
Without checking the book, basically two principle reasons
1) The surface railways which were prevented from crossing the Thames
concentrated on commuter services and built a complex network making
underground lines unnecessary to alleviate congestion (because the area
was not owned by so many influential people they could built on
surface/viaducts more easily).
2) the ground conditions were not suitable for cut and cover and by the
time tube tunnels were possible using a shield, the surface network made
competition unlikely to be profitable.

--
John Alexander,