THC wrote:
(Barking-Clapham Junction with no wires?)

I've always wondered about this too - it seems like a good fill-in
scheme that would be rather inexpensive. It would have the dual benefit
of releasing 150s from GoBLin duties and allowing through services as
listed from Barking, providing an alternate route for c2c users who
take the first train and change at West Ham for central London
destinations.

You might not even have to immunise the LU signalling either, which can
only help save money.