In message , Clive
writes

I thought all this rumour started because the American Embassy was
moving from *square to the New Covent Garden and wanted the Northern
extended down there from Kennington, where upon TfL said it would only
consider the route if it continued south to serve Clapham Junction.
Have things really taken hold enough for a serious bid from Wandsworth
to get it down to there and if so where will it terminate?

The trigger for the plan was the redevelopment of Battersea Power
Station, which is where the Northern Line extension is planned to end.
The developers of the power station (Treasury Holdings) are putting up
most of the funding, but the US embassy is prepared to contribute
because of the likelihood of a station at Nine Elms.

I can't see projection to Clapham Junction being practical, despite the
enthusiasm of the LB of Wandsworth - it would need substantial
rebuilding of the NR station, which is on a very cramped site and which
is of course incredibly busy. It's one of the main reasons why Crossrail
2 is planned to run further west (via Putney) - Clapham Junction is full
for the foreseeable future.

--
Paul Terry