Gary Jenkins wrote:

As an alternative to a Bakerloo extension is it feasible to hope for a
Jubilee line branch from North Greenwich in a south-easterly direction
towards Charlton. Eltham and Sidcup?

The problem is the alignment of North Greenwich station means that any
tunnel from there would have to go under the river. However, such a
tunnel could be constructed from W of the station, though the lack of a
step plate junction makes it more difficult.

This would be great for Eltham, as an elongated station (with
travelators instead of escalators) could serve both the station and the
High Street. I'm less sure about Sidcup - the residential density is
lower there, and there are already four bus routes linking it to Eltham.

Alternatively this could be a
completely new line going on northwards to Canary Wharf, Mile End and
Hackney and finishing off at Finsbury Park or Tottenham Hale.

I don't think a line that misses Central London would be worth all that
expensive tunnelling!