In the book, D'Artagnan doesn't actually become an official Musketeer until quite near the end, and we make quite a big thing about that. I won't give too much away, but when he finally does make it, they're not going to make it easy for him. That never changes.

It's not fundamentally different to any other genre, that action is a particular thing. Being able to do action sounds like it should be straightforward, but it really isn't. I always want the action to be witty. I don't want it to be merely routine.

In the book, D'Artagnan doesn't actually become an official Musketeer until quite near the end, and we make quite a big thing about that. I won't give too much away, but when he finally does make it, they're not going to make it easy for him. That never changes.

One of the problems of this genre is that there are cliches everywhere, and you've got to be careful and watch out. Our rule with cliches is to either gently acknowledge them and make fun of them, or do something else. Milady is, in one sense, a villain because she does bad things.

I think there's an element in Milady where she sees her own innocence in D'Artagnan. In the very beginning, she's using him in a pretty cynical way. When she gets to know him, she sees qualities in him that she recognizes and it's almost like trying to remake the past, but of course, it doesn't work.

The BBC came to me and they wanted to adapt the book [Three Musketeers] again, in the straightforward way, and I said no to that. I didn't want to do that. But what I did want to do was have a real look at the adventure genre because I thought it was ripe for reinvention.

You do see a few people and you are thinking of how that chemistry is going to work, but it's not really fair to put people who are auditioning together in a room. You have to make that judgement yourself, and that's partly where the casting director is so good. It was that blend that we were looking for.