I just love Nelson visually and heroically - he's such a great character, and I wanted somebody who would be stern and yet the perfect soldier. The idea is that they are soldiers in the greatest war of all in a sense, which I think is one of lines in the script. So Nelson was an easy choice.

Byron, I think, was probably Amber's idea. I'm not sure, but he's a perfect foil for Nelson in that way because he's the last person you would expect to be involved in the greatest war of all, or any war for that matter. So to have somebody who's so playful, who's childish in that way, [who's] lived such an interesting life [was good]. He knows that despite the fact that he's that way, there is something deeper inside him - he does have a lot more than he shows, and that he will participate in this.

As for Boadicea, we actually had a different queen originally in the concept - and I don't remember who suggested originally changing it to Boadicea, whom I wasn't familiar with at the time. Once I started doing research into who she was I said, 'Oh yes, we must use her.' Just the idea of the warrior queen was so wonderful and so apropos to what we were doing. And then because she was a queen, it just seemed natural that she should be the leader of the ghosts.