He'd probably have found that not a single person in that First Class carriage had the correct ticket! One reason I'd never buy a First Class ticket is because of this. I just couldn't bring myself to stand there and say 'I've paid for First Class, can I have someone's seat pls?'!
One night after work maybe about 10 years ago, the trains in London were all being cancelled (I can't remember which reason of the many choices it was). At Victoria, the concourse was full, the trains were rare. So if you saw one going in your general direction, it was advisable to squeeze on...