Lewis comes to an end this week - are you happy with how your character, DS Hathaway, has developed?

Well, they fleshed out Hathaway - he got his own set of demons. Something for me to get my teeth into.

What's it done to your profile - are you assailed by grannies wherever you go now?

No. I think I've only been assailed by one granny. Maybe I just don't have a very memorable face.

If Lewis runs as long as Morse, are you prepared to be known as Hathaway for ever?

I haven't thought about it. I don't really know any actors that aren't typecast, or at least I haven't met one. Gary Oldman maybe, but who else? Most people play themselves, pretty much.

You've played a young Prince Charles in Whatever Love Means. Did you wear prosthetic ears?

No. I wish I had, though. My ears stick out a bit anyway. I think that's why they cast me - to save money on prosthetics.

From what you learnt about him, do you think he'll be a good king, or a chump?

I think he'll be a good king, actually. I think he's got a good role model in his mum. Maybe on occasion he says things that are not totally on the money, but I love the fact that he has a little village [Poundbury in Dorset], and I love the fact he doesn't like horrible buildings.

You come from a veritable theatrical royal family yourself (dad James, Uncle Edward, cousin Emilia etc). What was charades like at Christmas when all you Foxes were growing up?

By the time it came around you'd have only had about two people playing because of the quantity of red wine that had been consumed. Christmas tended to be a laid-back affair. We'd get drunk once or twice a day. No competitive histrionics. No poetry readings.

Now you're making a name for yourself, is it a help or a hindrance being "a Fox"?

I don't mind it - I'm quite proud of where I come from, and I love my family and I'm where I am because of them. So I'm not in any way annoyed or irritated by it.

What are you up to just now?

I'm doing a play [Treats, currently on in London's West End] with Kris Marshall and Billie Piper.

Ah yes. Do you want to tell us all about your relationship with Billie Piper?

Not really.

Are you getting hassled by the paparazzi?

A little bit. She gets it. I'm not getting hassled by anybody. It's pretty tedious - it's not a job I particularly enjoy having to do.

One final question: are you looking forward to the inevitable Hathaway spin-off once Lewis kicks the bucket?

Ha ha. Bring it on! Maybe we could kill him quickly. I did recommend that we could have a scene in one of the episodes with me just holding his hand while he was in hospital and going, 'I'm so sorry,' and him whispering, 'Make sure the Force continues to work well. I'll miss you, Hathers. Look after it for me'. But, surprisingly, Kev doesn't seem too thrilled about that.