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Hey, have you seen my tits?” Michael Ball is showing me his breasts. “They’re 46EEE,” he boasts, as he wobbles them for my delectation. “Aren’t they just vile?”

They are. They’re also in a box, and they’re only attached to Michael Ball when he’s onstage. “It’s very uncomfortable,” he says. “My back’s killing me. Those tits are really heavy.” If this all sounds a bit incongruous coming from clean-cut West End pretty boy Ball (I’m not allowed to call him “housewives’ favourite”, for reasons to be explained later) – well, his new West End vehicle, Hairspray, is an incongruous show. And, in any case, Ball is no longer the pretty boy. “I’m older and I’m fatter,” he says, with a certain satisfaction. He recently gave up smoking. Then, “when this job came along, they said, ‘The fatter you get, the better.’ Well,” he beams, “that’s my kind of gig!” Can Michael Ball’s 2007 get any weirder? Before this year, we knew who he was. He was the Lloyd Webber crooner who belted out Love Changes Everything from the top of the charts. He was the Eurovision runner-up 1992, with the heartbreak ballad One Step Out of Time. He was theatreland’s Mr Safe, a Les Mis veteran you could trust with Chitty Chitty Bang Bang(he was the original Caractacus Potts) and draft in when Michael Crawford dropped out of Lloyd Webber’s Wilkie Collins refit, The Woman in White.

It was the last show that, like love, changed everything. Ball played the villainous Count Fosco, in a gigantic fat-suit. “So people saw me playing a comic, character role rather than what I usually am: the leading man,” he says. The fat-suit eventually made Ball (like Crawford before him) ill: “I was getting a succession of viruses then going onstage and cooking myself,’ he says. But the role propelled the 45-year-old star into a new career chapter, called middle age, “which is fantastic, because it opens up the scope of what you can play”. But there’s a flipside. “I look at Ben James-Ellis [his young co-star in Hairspray] and think, ‘Surely they meant me for that part? I could still do the 18-year-old hero!’ But that’s life. We are all moving on.”

Two examples of Ball’s moving on have thrust him on to the news pages in the last few months, to his great amusement. (“I’m an antiestablishment figure now! Right on!”) The first was Kismet,the ENO’s revival of Robert Wright and George Forrest’s 1950s musical fantasia set in, er, Baghdad. Ball was on Jonathan Ross’s show the other week gleefully slagging off the production, which he compared to Mel Brooks’s fictional Broadway farrago, Springtime for Hitler. He’s blamed both the director, Gary Griffen, and the designer, Ultz, for the show, which, in an ill-judged bid for topicality, featured explosions and rifle-toting squaddies amid the “Strangers in Paradise” romance. “It was embarrassing,” says Ball.

But doesn’t he take any responsibility for its failure? “I suppose it is unusual for an artist to be honest, and that’s a shame,” he says. But surely he could tell that this wasn’t the time for a Baghdad-set American musical? “I know what you’re saying,” he concedes. “Probably with hindsight it was daft. But the thing is, Kismet is such a good show! What’s wrong is not to have taken advantage of that, and to be so crass as to say, ‘Bring on guns, right at the beginning.’ You don’t need to do that. The audience isn’t that stupid.”

According to Ball’s version of events, he singlehandedly saved the show – “Someone had to hold the thing together.” He then moved on to another individual triumph: performing an unprecedented concert’s worth of West End and Broadway hits at the Proms. Classical musical purists were up in arms, which Ball can’t understand. “Were people upset that Shirley Bassey did Glastonbury? I don’t think they were. Would they have been upset if Pavarotti had done the V Festival? I don’t think they would. It’s not like classical music has one night a year at the Albert Hall, then that’s it. It’s got hundreds of concerts. So, get over it.”

The worst thing about the furore (“You’d swear,” says Ball, “I was responsible for global warming”) is that it threatened to ruin his fun. “You get so few opportunities to go, ‘Oh God, I can’t believe I’m here!’ And that was one of them,” he says. When he performed the concert in late August, Ball included a few digs at his persecutors – who responded in kind. AntiLloyd Webber snobbery was much in evidence, naturally. And “as a singer,” wrote this paper’s critic, “Ball is a reliable all-rounder rather than any kind of virtuoso.” Did this annoy Ball? Does he resent being thought of as middlebrow – naff, even? Well, maybe just a little. He’s fed up with the “housewives’ favourite” put-down. “You’ll always get lazy journalists,” he says, “and if they want to be really disparaging, it’s ‘darling of the blue-rinse brigade’. I don’t know if anyone has blue rinses any more. But it’s a nice little tag you can stick on.” But he can’t really deny the accusation. “A lot of people that follow what I do are certainly women of . . . a varying age range.”

There’s nothing wrong, of course, in entertaining women d’un certain âge. But the slur implies a safeness to Ball’s music – not to mention an emotive singing style that makes him irredeemably uncool. He certainly admits that “because of my acting background, there’s an expression in the way I phrase that can make you stop and listen”. But “people only talk about safe musical choices,” he insists, “because they haven’t done their research.” Audiences at his 2004 Donmar Warehouse cabaret show, Alone Together, witnessed Ball sing Radiohead’s Nice Dream, which prompted the thought that behind his cheesy-listening persona is a hip, down-with-the-kids Ball struggling to make himself heard. “There is,” says Ball, “something like that in every gig I’ve ever done.” (He recently performed Amy Winehouse’s Rehab) and he’d like credit for being bolder than his reputation suggests.

Hairspray will surely help. Already a smash on Broadway, it’s the musical of the camp 1980s film by that counter-culture hero John Waters, rewritten by Marc Shaiman, who scored “the greatest movie musical of all time”, says Ball, “which was South Park: Bigger, Longer & Uncut.” This is almost as weird as the tits moment, Michael Ball raving about the song Shut Your F***ing Face, Uncle-F***er. Hairspray is more family-friendly than that, says Ball, but it’s still “left-field, and really clever, and brilliantly realised onstage”.

Ball, plus breasts, is cross-dressing to play an “agoraphobic fat mother” called Edna Turnblad, whose plump teen daughter makes it her mission to racially integrate a local TV dance programme on which she has starred. The show also offers the spectacle of Ball in a romantic duet with his stage husband, the comedian Mel Smith.

“Without being preachy,” says Ball, the show “looks at really big issues. Racism in the 1960s; size-ism, and it looks at family, and how what on the surface is the most dysfunctional of families is actually the greatest of families.” In fact, it’s not surprising at all that Ball should find himself in a show that celebrates people being unashamedly themselves, whatever their critics say. Its opening song contains a lyric that might be his motto:

“I offer big love, with no apology.” Because, if he’s not always cool, and he’s not at all classical – well, does that matter, if he entertains people? Here’s what Ball is learning from Hairspray: “As long as people are good, and come from a position of tolerance and love and acceptance of others, then no one should impose any other standards on them.”

Hairspray, Shaftesbury Theatre, London WC2 (www.hairspraythemusical.co.uk020-7379 5399), from Oct 30; Michael Ball Back to Bacharach is out on Monday on Universal Music TV

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