In message , Rupert Goodwins
writes
On the train, the inspector took the ticket and said "You can't use
Network Card on this service, sir",

FWIW, my Network Card leaflet shows Gatwick Express as excluded. (Along
with HEx, Anglia fasts and CT Stansted to Ely (although this latter is
probably now allowed due to a recent rule-change).

My own gripe with Gatwick is that it's apparently impossible to buy a
"Any permitted" single to London [1]. Although if you buy a through
ticket to (say) Cambridge then the Gatwick to London section *is* "any
permitted". Go figure, as they say.

[1] And so you have to guess whose train will be next in. Or is this a
cunning plot to get people to use Gatwick Express and buy a ticket on
the train. Remind, me, who operates Gatwick??
--
Roland Perry