Michael R N Dolbear wrote:
So could I have taken the tube to Old Street via Stockwell or E&C with
a London Terminals ticket ?

I suspect not... Old St is on the list due to a special-case
interavailability with the Finsbury Park-Moorgate line from KX (eg you have
a season for a commute from Stevenage to Old St or Moorgate, on a Sunday
when the Moorgate line is shut you can go to KX and use the tube without
paying a tube fare).

I'd have thought Old St from the south would be barred for the same reason
that you can't go from Woking to Euston on a 'London Terminals' ticket -
Waterloo is what counts there, and you need to pay for the tube journey.
But I don't know the full logic for what counts as your last available
London Terminal (people can go through London Bridge and Waterloo East and
use Charing Cross as the Terminal, but can't go through London Bridge and
Blackfriars and use St Pancras).

Theo