peter wrote:
I will be travelling from London (Kings Cross Thames link) (KCM) to
Brighton on a Saver return (£24). (I am aware of the alternatives
via London Victoria, but will be arriving at Kings Cross from the
North so thought that would be easier.) I will be returning to London
a couple of days later, but need to get to Waterloo (to catch the
Eurostar). My question is will my return ticket to (KCM) allow me to
alight at London Bridge (LBG) to catch a train to Waterloo East
(WAE). Or will I just break my journey at LBG and take the jubilee
line to Waterloo (I still should have some PAYG credit on my Oyster
card).

If your ticket is a Saver (which is non-operator specific), then you would
be better off taking a Brighton Express service (Southern Railway,
http://www.southernrailway.com) from Brighton to Clapham Junction and
changing there onto any South West Trains (http://www.swtrains.co.uk)
service intoWaterloo mainline. It will be much faster (stopping only at East
Croydon) and will deliver you onto the main concourse at Waterloo.