In message , at
21:51:00 on Sun, 2 Oct 2011, Paul Cummins
remarked:
This is because the ticket is valid to more
than one London Terminal station provided it_s on any
reasonable line of route.

There is no reasonable route between Finsbury Park and Liverpool Street
via National Rail that doesn;t go via Cambridge.

A ticket to London Terminals doesn't give you carte blanche to travel to
*any* of them you choose, as the explanation I posted earlier makes
clear.

You could always go via Highbury and Islington, then Goblin to
Stratford, as a more reasonable route than via Cambridge; but it's not
allowed either.
--
Roland Perry