It's valid on any train operated by Govia Thameslink.
However if you use any trains operated by this company under their "Southern" or "Gatwick Express" brands, you could erroneously be charged for a new ticket or a Penalty Fare; if this happens you should appeal this, and contact us for assistance.
Such charges are rare, and when they occur, appeals so far have always been successful, in every case that we've been made aware of.
Govia Thameslink are in hot water over this and the matter is due to go to court later this year:
This press release hit the newswires yesterday: COLLECTIVE COMPETITION CLAIM AGAINST GOVIA THAMESLINK RAILWAY FOR OVERCHARGING RAIL PASSENGERS ON BRIGHTON MAINLINE SINCE OCTOBER 2015 London 6 July 2021 – An application to commence an opt-out collective action (“Claim”) was launched in the...
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