I don't know that the character develops. I enjoy playing it, it's fun, and I love doing audio stuff because normally I don't have to be on cameras like this. [That] makes it much tougher, and you have to fuss about things like what you're wearing and whether you look as if you're gone through a hedge backwards.

So I love audio things. It's fun because you work with different people. One of the things that's good about doing Shada is that it's Paul McGann and it's just very different. You get a different take on the Doctor's character which inevitably makes you react differently.

It's strange because the kind of banter that Tom and I had going isn't the same, but then it keeps you on your toes which is a very good thing. You're not thinking, 'Oh god, how did I do it last time?' you can just reinvent it with another person, which is a nice thing to do.