John was a single prisoner among the hundreds kept in captivity in the Colosseum whom the Tenth Doctor met when he was arrested for "borrowing" a horse. John's true name was never actually known, it was just a nickname the Doctor thought up when he named the only four prisoners who would talk to him. John was a bearded man.
John told his own anecdote after hearing Paul's involving a sword fight between two blind men. At the time he thought it hilarious, but once in prison he thought otherwise, saying, "Doesn't seem so funny now." Paul agreed with this statement.