Late response. Sorry.

Roland Perry wrote:
Most of the commuter rail in and out of London is at bursting point, and
has nowhere to scale *to*. It is at maximum capacity.

Much not most. There may not be much capacity for extra trains, but
there's plenty for making them longer. Last I looked, plenty of
trains, even at peak times, are 4 or even 3 cars.

There is a capacity problem on the tube - but even then mainly in
zones 1 and 2.

Colin McKenzie