My own personal hates:
People who board at London terminals in First Class and then walk through the train to standard.
THIS IS FIRST CLASS. ME AND A LOT OF OTHER PEOPLE PAID EXTRA JUST TO GET AWAY FROM YOU LOT. GET OUT OF MY CARRIAGE.
Of course, the worst are those who then stay in 1st class and pretend they didnt realise when their ticket is checked. These people should be thrown off the train. Whilst it is still moving.
Also, people who go to the attendant at the ticket barrier, and dont use the automatic barriers, even if they have normal tickets. If I have an ALR, it wont open most of the barriers. So I have to see the guy at the end. BUT YOU DONT NEED TO YOU IDIOT, GET OUT OF MY WAY.
And worse than those who take 20 minutes just to sit down, are those who take an equally long time to get up, subsequently blocking the aisle fiddling with their coats and luggage, whilst blocking other people from getting off the train.