I remember seeing an interview of him many years ago in England, when he was only recently become well-known because of the success of Monty Python on TV. He was rather serious and uptight, and said that he didn't like doing interviews and such, because people expected him to be funny all the time. And he basically didn't consider himself funny or a comedian : he was an actor, a comic actor, certainly, but he was an actor working from a script, and wasn't just funny all the time.
It's nice to see how he has mellowed out over the years.