How healthy are you?

I'm still working a 12-hour day without any problems. I've got high blood pressure, my hearing has got worse and I'd quite like a new pair of feet, if that were possible, but I'm pretty well.

Ever spent a night in hospital?

When I was doing National Service in Singapore I contracted a mystery infection which hospitalised me for about 10 days. As I recovered I was taken on outings with the wounded. I remember going to the races in my hospital blues.

Do you worry about your weight?

I worry a lot. I weigh myself every day. I used to come in at 10st 4lb for years, now I can be 13st 10lb - ghastly.

What exercise do you take?

I exercise every day. I've got a mini gym at home where I do pull-ups and press-ups and I swim regularly. Every now and again I still stagger around a squash court.

How do you relax?

There's nothing I like better than lying somewhere, preferably in the open air, with a very good book reading, dozing and undozing.

How much sleep do you need?

I don't need more than about six hours, or eight when I'm filming. I'm a good sleeper and I'm a great snoozer - I can sleep anywhere. I remember my father telling me that during the 1914-18 war he used to sleep standing up - I thought don't be silly, but I can almost do that.

Attitude to smoking?

I hate it. I stopped smoking 30 years ago. I was working in medicine at the time and I saw doctors who were smoking 80 a day stop when the cancer report came out. I evangelise about it.

Are you happy?

Yes, on a scale of one to 10 I'd put myself at an eight. Despite being known as Mr Grumpy, I'm happy a good deal of the time.

Is sex important to you?

Of course, but the ageing process has its drawbacks. I think the recent chemical advances are excellent - I've made use of them, shall we say.

How do you feel about cosmetic surgery?

When I was younger, if there was a 100 per cent guaranteed way to stop hair loss I would've been interested, but I never think about cosmetic surgery.

NHS or private?

I'm very proud of the health service because I worked in it for 10 years, but I'm private, for selfish reasons, really. As an actor, I only have myself as an instrument so I need to have it tuned at the drop of a hat. Also, I just don't like sitting in crowded waiting rooms with people gawping at me when I'm not feeling very well.

· Merlin starts on 20 September on BBC1 at 7pm