.....but the fact Southern refund everyone who gets excessed tells it all....
Considering that the department that actually issues those refunds is the one that has a job of getting you to travel with them again after "things have gone wrong", it doesn't actually tell us anything, except, of course, that passengers can do no wrong, even when they are wrong, and screw the staff who actually try to follow the rules laid down by the railway.
The "Not Gatwick Express" routeing is not a valid entry in the route field, but there is no decent 'ombudsman' / 'regulator' to enforce this. No tickets should use that routeing as it does not fit within the definition of the NRCoC....
I sorry, but I don't recall any of the NRCoC conditions banning the use of trade names in the route field, care to point it out to me? (and then justify TPE, VWC, XC and LM).
....In the case of the latter, travelling on any service operated by Southern is complying with the restriction (not that there's much chance of an on-board ticket check these days anyway!)...
If, as you seem certain, Gatwick Express is not a train company (as defined in the NRCoC), then Southern does not have to put the prohibition on the ticket (because it is not a train company) if it wants to ban them from certain tickets.
If you are wrong and Gatwick Express is defined by the NRCoC as a train company (it is listed as one in the NRCoC definitions), then 'Southern Only' and 'Not Gatwick Express' would prohibit use on Gatwick Express services (or, if you prefer, services run under the brand (or trading name) Gatwick Express).
Regardless of either being true, is it not better to let people know of the prohibitions, rather than leave the passenger at the mercy of the evil railway people????
....It's interesting that Southern do not charge a new ticket (which they would be entitled to, if it was a different Company's ticket, e.g. FCC Only) and instead charge a nominal excess....
If the ticket were valid, they could not charge an excess, so perhaps they are simply doing everyone a favour by not issuing a new ticket????
....And equally interesting that, in all cases of the excess being charged that I know of, more than a full refund was given....
Though on a previous occasion you admitted that you could not say you knew of all people given the excess, and therefore could not say if the total you know of is 1% or 100% of all the cases, and once more we have to look at the department that issued the refund, you know, the one that wants you to travel with them again.
Do the barriers for the dedicated non-stop to Gatwick Airport services at London Victoria accept SOUTHERN ONLY tickets, I wonder?
It wouldn't make any difference to validity either way.