John Barrowman, entertainer extraordinaire, screen and stage star, is a fairly fine forty-something.

Classically handsome, he does occasionally suffer at the hands of the make-up department who have a penchant for orange foundation, and certain cruel friends of mine accuse him of looking slightly ‘plastic.’

When I meet him in the flesh (and fabulous flesh it is), Barrowman is radiantly beautiful. His skin glows, his eyes are luminous, and he is palpably alive; he looks little older than thirty.

How does he stay looking so good? ‘I drink two litres of water a day. I do drink alcohol, but not to get drunk, I don’t binge drink. If I’m sitting down to dinner, I won’t drink soda, I might have the odd glass of wine, but I’ll drink water.’

I’m sceptical; surely there must be more to it. ‘Well, if you ever need a little bit of help’- he tweaks the corners of his gorgeous eyes, and winks – ‘I’m all for it.’

He exudes vitality – and he certainly needs plenty of energy to keep up with his hectic schedule. But Barrowman doesn’t resent marketing his work. ‘I think of myself as a business – a product.’

After all, he points out, ‘If you become an actor, it’s always at the back of your mind: you could become famous. You shouldn’t pretend to be surprised or angry if it happens.’

This is a man who is booked until 2011 and is thinking even further ahead, planning a return to his first love, musical theatre – a genre he staunchly defends against detractors.

‘I’ve done “serious” theatre, I’ve done Shakespeare… I don’t see anything different about performing in musicals; to me they’re just as serious.’

Musicals are what Barrowman does best; he has appeared in numerous productions in the West End and on Broadway, including the National Theatre’s Anything Goes: ‘That was absolutely one of the most amazing experiences I’ve ever had.’

Currently in talks with Andrew Lloyd-Webber about a sequel to Phantom of the Opera, Barrowman’s also being wooed by Cameron Mackintosh, who wants him to play the title role in Barnum.

‘I’m inclining towards Barnum,’ he says. ‘It’ll mean getting back into serious shape, better than ever before. I haven’t been to the gym in seven months, I haven’t had time, I’ve been so busy with work.

But I’d have to do two months’ intensive circus training to do Barnum.’

Circus training brings to mind spangly, tight-fitting clothes, which would show off that rather fine physique to even greater advantage.

‘God, no, I won’t be wearing lycra,’ he exclaims in horror. And then, with a lingering touch on my shoulder and a glint in his eye, ‘Well, I’d be learning all the trapeze stuff and everything…I suppose maybe a pair of cycling shorts…Or they might even give me a leotard…’

Barrowman is the world’s most outrageous flirt, and delights in being provocative. Even his acting smacks of promiscuity: ‘Whenever I’m playing opposite a leading lady, or leading man, I have to fall in love with them a little bit, for it to be truthful, even if it’s not a romantic relationship.

I have to be in love with them.’ Women as well as men? ‘Yes, I never define myself – it’s unfair. Being gay, it doesn’t mean I don’t fancy women and think they’re beautiful.’

Yet this is all for show. He’s been with his partner, Scott, for nearly 15 years; they celebrated their civil partnership in 2007. ‘A civil partnership is not a marriage,’ Barrowman explains.

‘It’s about being recognisable to society and government, being equal to married people, it’s not actually being married.’ He objects to the terminology; for him, marriage has inescapable religious connotations.

‘Marriage means being part of an organisation that thinks I’m evil.’ He doesn’t just mean the Church. ‘It’s any religion really – they all want to get rid of me because I’m a gay man.’

The issues surrounding the societal acceptance of homosexuality are so important to him that Barrowman is currently filming a BBC documentary, The Truth About You, which aims to discover whether sexuality is determined by nature or nurture.
‘I’m undergoing loads of tests… I believe you’re born gay, but I think environment also has something to do with it. It’ll rock my world if we find out you’re not born gay, so I’m taking a big risk.’

Barrowman is happier about his big break, playing Captain Jack Harkness in the BBC’s Doctor Who and the susequent spin-off, Torchwood.

‘It was a little boy’s dream come true. If I only had to play Jack for the rest of my life, or for the next 15, 20 years, I’d be totally content,’ he says with a grin.

‘I don’t think of him as a character. He’s part of me. It was the easiest casting decision the team ever made; as soon as they saw me on the tapes they said, “That’s him!”’

John and Jack share many traits; they’re expansive and exuberant, and compellingly attractive. I ask how John feels about David Tennant; Jack certainly fancies the Doctor… ‘Jack sees that, I don’t. David’s not my type, he knows that.

We joke about it. People ask if we’d sleep with each other for a million pounds. We look at each other and go, “Ten grand, I would!”’

But if Jack’s a part of John, does that mean Barrowman never stops acting? ‘Oh my GOD!’ leaning forward for another firm but feeling touch on my arm, ‘of COURSE I stop acting!’

This seems rather dramatic, in every sense; I suggest he might be acting all the time. ‘God, no, I’m not acting now,’ with another caress.

‘This is the real me! Scott does say to me sometimes when I get home, ‘Come on, sit down, slow down, you need to relax,’and I do need to switch off. But you can always tell when I’m acting and when I’m being me. There’s a definite distinction. I’m a very real person.’

He may seem too good to be true, but Barrowman is real – I know, I saw him, I touched him, and will be dining out on the story for some considerable time to come.

I nearly ran him over on my bicycle on my way home, as he walked back to his car in the late-night drizzle.

I wonder if he would have come back to life? I like to think so.