Are you looking forward to the opening night tonight? "Yes, though I'm pretty exhausted already. I was singing the show to myself in my head last night. I sang through it three times, and as you know, it isn't a short show!"

Are you the only new boy in Les Miz? "No, there are about 20 of us starting on Monday, July 28, so it doesn't feel too strange, and there's that energy that you always get when there are a lot of new people around."

Is this a part you had an ambition to play or is it something that just cropped up at the right time? "Actually it's something I've always wanted to do, and it has been a dream of my dad's for me to play Marius. The opportunity to play the part coincided with S Club finishing, so it was very well-timed as far as I was concerned. I auditioned in the normal way and got the job."

Do you have a favorite song from the show? "There are a lot of great numbers, but I guess if I had to choose one it would be 'One Day More' at the finale of Act One." Do you get to see much West End theatre in your time off? "I saw Our House recently, which I enjoyed. And The Woman in Black, which was really scary!"

You've had a very long career in theatre for someone still young? "Well, I started very small! I went to stage school and was a child actor — in Oliver! for example. I'm looking forward to being in Les Miz for a year, and then I'll try a different sort of acting — in film or television perhaps, though if another musical came up and I thought it was right for me, then I'd happily stay in the West End."

Have you anything to prove by taking this role on? "Up to a point, in that I think a lot of people feel that having been in a pop group you are cast for the celebrity that goes along with that, rather than for being an actor. Whereas as we've discussed, I have trained as an actor and singer since childhood and already have a lot of experience of acting, on stage and elsewhere, so I hope my performance will demonstrate that I was cast for my ability rather than for membership of a group, however successful that group may have been."

How are you going to cope with the heat if it carries on? Well, there's no air conditioning on stage, you rush about a lot, and there's the heat of the lights, plus you're in make-up and wearing uniforms, greatcoats and so on, so by the end of the show — and I know because we've been rehearsing for over four weeks — you're drenched in sweat. Thankfully the Palace has showers!"

What about post-performance refreshment? "The cast like to socialize afterwards. There's no particular pub — I think the whole of Soho is fair game! But when you've given a performance you're on a high, and want to relax with your friends before heading home. I hope the audience are on as much of a high as we are..."

Jon Lee can be seen in Les Misérables at the Palace Theatre.