On Mar 4, 9:36 pm, "Peter Lawrence" wrote:

Not necessarily. From St Albans I can get a ticket either to
Farringdon Und, route Not Underground, or to London Thameslink. ISTR
that the latter did not work the barrier at Farrongdon but was
accepted by the barrier staff.

Where the hell is Farrongdon? No wonder your ticket didn't work :-)

IME there were a couple of occasions when my London Thameslink ticket
failed to work the gates, but now all is hunky dory. Whenever possible
I try to get a London Thameslink ticket because of its additional
flexibility in Central London (when compared with destination-specific
tickets that have the same route validity).

Intriguingly (is that a word?) some tickets from the north to City
Thameslink southwards are still sold as route Any Permitted but at a
premium compared to route Not Underground tickets, which are now the
'standard' option and are sold for what the former were sold for (when
adjusted for inflation) until this year.