Southern comfort
Sir,
It only serves to underline ‘Dr B Ching’s point, but due to a complex technicality, Southern only tickets are actually valid on Gatwick Express services. There are multiple reports of fines issued being overturned on appeal (search Reddit & railforums.co.uk). This is because only restrictions based on a train operating company (TOC) can be issued, with Southern & Gatwick Express services being operated by the same company (Gatwick Express merely being a brand), such restrictions cannot apply. I would get out more, but I’m too busy planning the most cost-effective way to get from Aberdeen to Penzance.