In my carriage there were two Irish blokes. One of them seemed to be the more lucid. The other was large, loud, and foulmouthed, and punched the first one.
At Green Park, he blocked the aisle and refused to let passengers move down. After his companion shouted at him, he screamed "FUCK OFF YOU WANKER" and stormed into the next carriage. At this point, the tube station workers were nervously gathering on the platform, and the driver made the following announcement:
"Ladies and gentlemen, I'm sorry for the delay. There is a lunatic on the train, but once we get him off, we'll be on with our journey."
I later saw the aforementioned lunatic wandering around Victoria Station looking for someone to shout at.