Why can't passengers upgrade on board GTR services?

[WesternLancer]

Moderator note: Split from

HELP! Can anyone advise me on how best to contest a penalty fare issued by Govia Thameslink

Hi all, I was issued with a penalty fare on the Gatwick Express just before christmas. Can anyone advise my how best to frame an appeal, please? My colleague and I were travelling from London to Brighton for work We both separately purchased off-peak return tickets on the Trainline.com and...

www.railforums.co.uk

Is there any reason why passengers can’t pay for first class upgrades on board? Are these trains one person operated?

I would assume on an ‘inter city’ type service that would be possible. When Gatwick Express operated as a separate franchise (and not to Brighton) am I right to think that was in fact possible.

 

[AlterEgo]

Is there any reason why passengers can’t pay for first class upgrades on board?

There is no entitlement to do so under the NRCoT, regardless.