Ian F. wrote:
Apologies, Ralf and Bob - clarification required. I just needed to know
which out of LB or Waterloo was the quicker and easier to change from
Northern line northbound to Jubilee line east/westbound.

I'd say LB. The exits on northbound Northern line trains are
near the back of the train at LB. If you've got heavy luggage
go up to the ticket hall on the escalators, then back down again
as it'll probably be a bit less of an effort than using the
usual walking interchange.

#Paul