Dear Rob in Chicago,
Lis Sladen left the series because she was convinced that the new producer, Philip Hinchcliffe, would prefer a companion of his choosing; in other words she felt as Barry Letts had chosen her then Philip would pick someone else. She was badly mistaken, Philip loved Lis's work and was very fond of Lis as a colleague. All this came out later and made me grind my teeth with resentment. Anyway I felt the loss terribly and became withdrawn and moody. And then came Louise Jameson. This story, like me is now very old. Louise found me cold, aloof and not fun to be with: sad eh? And now, in another millenium, I often work with Louise and I am so happy and fond of her. All those wasted hours being cold and aloof!
There are a good few adventures coming out soon and I hope you like them. I have even done the parrot in Treasure Island. And Long John Silver too, of course, for Big Finish. Check it out here: http://www.bigfinish.com/news/v/tom-baker-in-treasure-island.
That brought back memories of a long gone agility, I was a great hopper in those days.