The day before I am due to interview Hugh Jackman, the Australian actor drops a tantalising hint on Twitter. "Hey tweeters, I have something exciting to announce soon," he writes. "What could it be?" What indeed? I can't help but think back to the last time I met him, shortly before the release in 2006 of The Prestige. Christopher Nolan's thriller about two rival magicians (the other was Christian Bale) contains Jackman's richest screen performance to date: he reveals hidden torment behind the conjuror's curtain-calls-and-bouquets persona, one that he will know from his parallel career as a lead actor in musical theatre (an existence of which the majority of X-Men fans are probably oblivious).

The Prestige was a mystery wrapped in an enigma, then padlocked in a chest and dropped in the ocean. Some people think the same applies to Jackman. A friend took me aside and asked whether I really swallowed those "ordinary, boring family man" quotes fed to me by Jackman. Couldn't I see this was a classic cover story? Jackman has encountered such talk over the years, and always has a smiling riposte at the ready: "You really know you've made it when the gay rumours start."

I tell Jackman that his Twitter tease convinced me he was about to come out, and he humours this with a raucous laugh. Then again, some people would consider his eventual announcement – that he is bringing his one-man song-and-dance show to Broadway in mid-October – to be tantamount to bounding from the closet, anyway. He laughs at that, too, which is very game of him. He even throws in a slap of the thigh: his thigh, that is, not mine. It all makes for a cheerful alternative to the usual "No comment."

He's been through this before, a long time ago. When he was 10, a teacher approached him after the end-of-year school concert to compliment him on his dancing skills and to advise him to sign up for dance class. His father was all for the idea, but one of Jackman's older brothers told him dancing was for sissies: "What are ya – a poof?" he jeered. "I wasn't 100% sure what that was," the actor says now. "But I knew it didn't sound like something I should be. And that was it as far as dance. I shut it down. I was just too embarrassed. I'm the 10-minute Billy Elliot. 'I wanna dance!' 'You poof.' 'OK, I'll be a miner.'"

His brother apologised when Jackman was 18. "That released something for me. I literally signed up for a tap class the day after he'd said sorry." Slightly sadly, he adds: "Of course, I was fully aware I'd left it too late to turn professional." That said, he has to be positively restrained from hoofing in public. After stints on some minor Australian TV shows (including Corelli, on which set he met his wife: she played a prison psychiatrist, he was a tattooed inmate), his acting career took off in musicals, beginning with Trevor Nunn's National theatre production of Oklahoma! in 1998.

We are talking during the London stopover in the international publicity tour for Real Steel, the world's first (and possibly last) touchy-feely boxing-robots movie. Somewhat improbably, Real Steel is The Champ meets Short Circuit, with a Crazy Heart country-and-western vibe. Jackman plays Charlie, a washed-up ex-fighter who enters hulking robots into showdowns at country fairs. Who else but Jackman could put vim into the ringside gibberish he is called on to holler ("Bring it! One, two, overlord! Shatter punch!")? Who else could pull off Charlie's grudging affection for his long-lost son, a blond-haired tyke with Shirley Temple pluck, without making the audience gag on its popcorn? But then Jackman has always excelled at bringing charm and sincerity to pictures that would sink a lesser showman.

More interesting than Real Steel's combat sequences, which resemble an uprising in a car assembly plant, is Jackman's relish at shedding his slick, soft image, at least for the film's first half. "It was so much fun to see how far we could take Charlie," he says. "This is a DreamWorks picture being distributed by Disney, and our lead character sells his son in the first 20 minutes. I really liked that. When we showed it to the studio I thought they were gonna tell us to reshoot. I'd already asked Shawn [Levy, the director]: 'Are we making him too much of an asshole?' The studio thought we'd pushed it but that it worked."

Free of the physical heft required of him in Real Steel or the X-Men series, the 42-year-old is tall (6'2") and lean. Dressed in black shirt and trousers, he resembles a giant chess piece. His manner is as courteous as a bellhop who's banking on a big tip. Perhaps that's another reason why he savoured the sleazier aspects of Charlie's personality – it gave him a chance to go against the grain of his personality. "Absolutely. I loved it. I don't allow myself to be like that in life, you see."

Or on screen, come to that. Beneath the snarling and the tantrums, Wolverine is just a pussycat. The rough-hewn Drover in Baz Luhrmann's sweeping, silly Australia is essentially a Playgirl pinup minus the staples. Even when Jackman tries for sinister, in Deception or Woody Allen's Scoop, it's the suave front that is more convincing than the menace beneath. He has gained a reputation as the stand-in man – he only got to play Wolverine when the original choice, Dougray Scott, was unavailable, and he has stepped into parts vacated by Brad Pitt (The Fountain) and Russell Crowe (Australia).

More telling are the roles Jackman almost played. He got as far as his costume fitting for the professor seduced by Nazism in Good, but then funding fell through (it was later filmed with Viggo Mortensen). And he was once the lead in Drive, back when Neil Marshall was attached as director. Either of these parts would have demanded a moral ambiguity rarely seen among the roles on Jackman's CV.

He's self-deprecating about the luvvie side of himself; the way he tells it, he had to be discouraged from giving Wolverine jazz hands. "It takes every ounce of power in my body when I'm playing him just to keep still and find that interior, brooding aspect. [Director] Bryan Singer used to yell at me: 'Stop moving! Just stand there and say your lines!'" But when I suggest that The Prestige worked so well because it played his glossiness against Bale's method intensity, he seems offended. There's an awkward pause, and I ask whether this isn't how he sees himself. "Not really," he shrugs. "I know I'm not known as method. By nature I'm not a brooder. What I continue to use is a mixture of the English school, which is traditionally outside-in, and the more American way of working from the inside out."

It's odd, given Jackman's love of musicals, that he hasn't appeared on screen in one yet, but that will change next spring when he begins shooting Les Misérables, directed by Tom Hooper (The King's Speech) and co-starring Russell Crowe and Anne Hathaway. Then it's on to the much-delayed second Wolverine movie. A start date has come and gone several times this year: it was going to be shot in Japan, but the earthquake hit; then Darren Aronofsky dropped out as director. Despite the setbacks, Jackman remains confident the picture will compensate for the shortcomings of its predecessor.

"I think we've got the chance to nail the character this time, to do the hole-in-one. We haven't managed that yet. On the last movie, we complicated it with too many other characters. And there'll be more women this time, which is good. The last one was so masculine! The new film will go more into the character. I don't think we've ever seen his rage expressed properly. We're letting go with this one of the whole 'Who am I? Where did I come from? Oh no, I've lost my memory' thing. I feel like that's sent us all to sleep. 'Yeah, whatever pal. We're bored! Fine, you were a sushi chef, whatever it was, can we just get on with the story now?'"

Real Steel is released next Friday.