On 1 Jan, 14:22, wrote:
The larger scheme now being looked at is probably the most likely to go ahead - the extra expense but is more than compensated by the far greater benefits especially to the SWML.

That is probably the better choice. At the moment, as I read the
Modern Railways article, they have not narrowed down the service
groups on the SWML. Taking on too many is a recipe for poor
timekeeping.

This is why proposals for taking over the Wimbledon branch are now looking unlikely as the tunnel will probably need to extend at least as far south as Wimbledon to allow certain services to be diverted off the mainline.

That said; the subsurface network badly needs simplification.