I thought I would mention this on here as travelling by train, not tube, allows me time to think. My biggest pet hate regarding train travel is people who put their feet up on the seats. If you are going to do this you might as well sit on the floor. Other people have to sit on the seats opposite you and by putting your feet on those seats, with the shoes you have tramped around London in - who knows what you have walked in or over. London has a range of items, such as chicken bones, spit, oil, hair and other nasties on its streets and you 'put your feet on seats people' put this on the seat I want to sit on.
I once saw a man pick up a Metro or it may have even been an Evening Standard and place it on the seat in front of him, then place his feet on the seat. This I guess I have no complaints with as he didn't put his feet directly on the seat. The only person to taken anyone else into consideration, when it comes to feet on seats in London.
Another thing, whilst I am on train travel is people who insist on sitting in the seat closest to the isle, and they are getting off at the terminating stop, making you climb over them to get to your allocated seat. Then they wonder why you have give them a glance of despair when you sit down.
One last thing on train travel, is individuals who insist on sitting on the middle seat of a row of 3, why not sit next to the window out of the way and let someone else have the 2 extra seats you are filling up with your bags.