I went and saw a pantomime in Bath when I was in the UK. Indeed, I managed to persuade my mother to arrange the trip to Bath around the panto dates so I could see it. The reason? Colin Baker (whom I wouldn't call a has-been) was in the show. It was Jack and the Beanstalk, and Colin Baker was the villain, Fleshcreep.
It was...quite the experience. Seriously. Besides being strangely highly entertaining, you will never hear anything like Colin Baker singing Let's Do The Time Warp Again from The Rocky Horror Picture Show. He didn't quite hit all the notes, but he more than made up for it with that damned powerful, operatic (yes, operatic) singing voice.
Four minutes? That's ages! What if I get bored? I need a television, a couple of books. Anyone for chess? Bring me knitting.
-The Eighth Doctor, defiant in the face of death, in Doctor Who: The Night of the Doctor