Congratulations on presenting the Oscars. How free were you to do your own thing?
Very free. They basically said, “You come out, do your six or seven minutes, and then we cut to…” and I went, “Hang on, what’s in that six or seven minutes?” And they said, “Whatever you want. You work it out!”

So you came up with all of that yourself? The speech, the dance, the gags…
The great thing about the Oscars gig is that you can call up anyone. I love Ricky Gervais, so I rang him and said, “Hey, what about this…?” And Ricky just said, “Right…” and it’s boom, boom, boom, straight off the bat.

Were you told what to do if Kate Winslet refused to leave the stage?
Just tackle her. I’d have to just applaud and say, “Great speech Kate, now get the fuck off the stage!” No, that’s what the orchestra’s for, they just start playing. When the bongo drums start, you know you’re crapping on too long.

Did you miss being a part of the crowd?
I missed the drinking games. In Australia you pick a word, like ‘agent’, ‘lawyer’, or ‘God’. Then whenever anyone mentions one of those words, you have to skull your drink. Whoever has ‘agent’ always gets the most paralytic. ‘God’ gets you pretty drunk, too.

Is it bad form to nip off to the toilet?
People very rarely stay the whole time. Within an hour the bar fills up, so they’ll have a lot less shots of the crowd because it’s just seat fillers. As a host I looked forward to the seat fillers because they laugh at everything.

You’re a big star now. Is it hard to put us normal people at ease?
John Travolta handles this best. When people meet him – intelligent, grown-up people – they just babble. The words don’t come out. And he’s great: he just looks them straight in the eye, talks to them very calmly, and lets them gradually find their feet. I really admire that about him.

Aussies are notoriously manly. And you’ve done a few musicals, which, er, aren’t. Do your mates take the piss?
Not really. When I played Peter Allen [gay Aussie icon from massive Broadway musical The Boy From Oz] people gave me a hard time, but the Americans are the most uptight about it. I did an interview with Barbara Walters and she said, “When you played Peter Allen, you did it so well. There were rumours going around that you were actually gay…” I took it as a compliment. You’re not anyone until someone says you’re gay, ha ha!

Moving on: what’s the most embarrassing thing that’s happened to you on stage?
I pissed my pants.

Okay, that’ll need an explanation.
I was doing Beauty And The Beast, and I was getting dehydrated. So that day I drank four litres of water, and by the time I got to the final number I was dying for a piss. In the end I had a choice of not singing and holding it in, or pissing my pants. So I sang the big final note and just started peeing, I thought the tights must be like a scuba suit. I carried on singing for two minutes, then made an exit. My dresser looked at my crotch with a horrified face. It was completely dark.

I also remember having a migraine when Tony Blair came to see Oklahoma. I was going into the wings and throwing up whenever I was off stage, and afterwards Tony Blair came back stage to meet the cast, and of course I was throwing up. He probably thinks I’m a Tory.

Isn’t that what an understudy is for?
Come on mate, we’re Aussies! You throw up and get back out there.

Think there’ll be an X-Men musical?
I don’t think so. We’ve done a few outtakes, but they will never see the light of day.

You’re in pretty good shape in Wolverine. Is it true you were benching about 300lbs?
Maybe a little north of that. At my height I was lifting some pretty heavy weights. After three movies as Wolverine, I had an image of how I wanted to look. Veiny and lean – I kept thinking of De Niro in Cape Fear, because the moment he took his shirt off you thought, “This guy’s a freak.” Wolverine is half animal, half human, and I wanted a body that reflected that. But the food was the big change.

What did you have to eat?
I needed a full meal before I trained, so I’d have egg whites and dry toast at 4am. Then go back to bed. Then wake up, train and have a protein shake. At 10am, I’d have two chicken breasts with brown rice and steamed veggies. At about 1pm, and every three hours after that I’d have a meal of protein and steamed vegetables, no carbs, and another protein shake. It was a lot of food, about 4,000 calories a day. I did that for nine months.

What does the wife think of your muscles?
She wasn’t a huge fan. She said my job as her husband was “to be fat and ugly”. That’s going to make her look better, so that’s all she asks of me. Sometimes she’d just look at me and go, “Who is this guy in my bed?” And let’s face it: with all those protein shakes, the farts are pretty bad.

You worked in your gap year at Uppingham School near Leicestershire. How was that?
I’d just left high school and I was an assistant boarding master; I was just a dogsbody. I worked with the PE teacher and with the drama department. The hardest thing for me was that girls were there and I couldn’t cavort with them. They were 18 years old. It might have even been illegal. The headmaster pulled me in, welcomed me to the school and said, “Now, listen…” He put the fear of God into me.

You played rugby. Any nasty injuries?
If I didn’t have blood trickling down my head I didn’t feel like I’d played a game. I was always getting my head kicked in. One time I remember taking a ball from the kick off, I jumped and the guy tackled me in mid-air off the side. There was a drain and as he smashed me, my head hit the cement. I woke up in hospital a few hours later.

You sang the Australian national anthem at a Bledisloe Cup match in 1998, too…
That’s the most terrified I’ve ever been. The Melbourne Cricket Ground holds 100,000 people, and it was packed. I was standing in front of the southern stand, which holds 30,000 people, when I suddenly realised they were all in black – it was the New Zealand package deals. I was introduced to sing as, “The star of stage and screen…” when I’d only been in one movie and one show. I just got this massive boo from 30,000 New Zealanders.

Terrifying. Did Christian Bale ever threaten to “kick your fucking ass” on the set of The Prestige?
Ha ha! No, he didn’t.

X-Men Origins: Wolverine is out on April 29