At a rehearsal in North London – in a huge, wooden-panelled room that looks, and smells, like the assembly hall of a 1930s grammar school – the biggest live show of 2008 is being pieced together.

Over the next two months, Strictly Come Dancing Live takes the BBC’s phenomenally successful show to 40 sold-out arenas. Stars from all five series – Zoë Ball, Chris Parker, Denise Lewis, Letitia Dean, Matt Di Angelo, Darren Gough, Louisa Lytton, the semi-celebrity chef James Martin, another sportsman, someone whose name I didn’t catch – will be tangoing, fox-trotting, waltzing and cha-cha-cha-ing in front of an omni-generational audience – and the judges. It will be a glitzy, glamorous, well-drilled tribute to the beauty of the discipline of dance. It will evoke the heady days of the Mecca Ballroom, but with all the benefits of modernity. It will be a triumph.

That’s the idea, anyway. In actuality, on the first day of rehearsals, getting the celebrity dancers into any form of crack hoofing squad is proving a nightmare. “I did have to shout at them this morning,” says Arlene Phillips, Strictly Come Dancing judge and co-producer of the live show. She’s looking stern sitting next to the tea urn. She has a head-cold, is dressed all in black and looks as if she might lock bad celebrities in a cupboard, should they vex her.

We both gaze upon the celebrity dancers before us. The semi-celebrity chef James Martin is sitting on a chair, still a little dazed, having previously fallen over and banged his head. Zoë Ball is telling a very amusing anecdote that, even from the distance of the tea urn, is clearly both filthy and libellous. The cricketer Darren Gough is doing what a teacher would call classic mucking around – pulling silly faces, pretending to dance in a “gay” way. Matt Di Angelo, of EastEnders, and his dance partner Flavia, tabloid hot properties and alleged lovers, are in a corner, in a quiet world of their own, practising a Latin step that necessitates their pelvises be glued together at all times. And EastEnders’ Chris Parker and his dance partner have disappeared outside for a fag.

“I mean,” Phillips continues, in her imperious Russian-dowager manner, “many of them turned up late, because of misbooked cabs and so forth, and that’s forgivable. But then to come in and giggle all the way through – it’s unacceptable. It’s like every day is the first day at school.”

She rolls her eyes up to the heavens. Some manner of squealing breaks out around the nucleus of Parker and Gough. A small female dancer has her hand over her mouth, trying not to laugh.

“Excuse me,” Phillips says, walking onto the dancefloor and clapping her hands. “Right everybody! Playtime’s over!” As if to underline the chill of her words, as she walks, a single, dry autumn leaf mysteriously falls from her trouser cuff to the floor. I’ve Had the Time of My Life strikes up on the PA. Phillips and choreographer attempt, for the fifth consecutive hour that day, to bring the Strictly Come Dancing All Stars to the live stage. From here, it looks like a task slightly more difficult than herding cats.

Strictly Come Dancing is as big as the BBC gets. It’s a total smash hit, beating the more feverishly-hyped X Factor in the ratings, getting tabloid headlines and being widely credited with sparking the huge renaissance in ballroom and Latin dancing in this country.

While the format is king – a collection of celebrities in faintly ludicrous costumes attempt weekly more complex dances, until a winner is declared – it is far less in danger of becoming an exhausted mechanical TV process as is I’m a Celebrity – Get Me Out of Here! or X Factor. This is because, in the main, Strictly Come Dancing harks back to a simpler, gentler, more gentlemanly era of broadcasting .

It’s all about the transformative pleasure of some nice celebrities learning a new skill, with a generous tot of camp razziness thrown in.

As the almost pointlessly beautiful Di Angelo puts it, in a break from rehearsals: “It’s a good-natured family show, isn’t it? Probably the only one left. We all put some work in. We’re not just in a forest, eating kangaroo bollocks.”

Indeed, it’s a measure of the show’s desirability that the celebrity lineup for next year’s show is already booked up. It’s seen as an almost certain aid to a celebrity’s career, as opposed to an appearance on I’m a Celebrity . . . or Celebrity Big Brother, which are more apt to be a risky, double-edged sword.

Promotors have been keen to book a live show since the broadcast of the second series, forecasting, accurately, that its ticket sales would dwarf tours by both Take That and the Spice Girls. But it was only last year that the BBC was finally persuaded to license the format.

Paul Roberts, who works for the promoters Phil Macintyre Entertainment and co-produces the live show, runs through the contents.

“It’s basically like the live [TV] show, but with some ‘special bits’,” he says, sitting at the back of rehearsals, and laughing every time someone makes a mistake. “Solo numbers, judges, etcetera. The arena audience can text-vote there and then, so every show has a winner. The vote money goes to charity. There’s a couple of big professional numbers, a 16-piece band, big chandeliers being raised and lowered. I’ve got 110 people on the road.” He gives a meaty sigh. “It’s costing me a bloody fortune.”

Anyone who’s watched the TV show might be a little mystified as to why Alesha Dixon, the “sizzling” winner of the last series, isn’t in the lineup. Roberts explains that Dixon has commitments in Japan, and that the aim of the show isn’t necessarily to have the best dancers on, anyway.

“Part of the appeal is people like Chris Parker who are, for want of a better word, a bit crap, but keep on having a go.” As if to underline his point, Parker takes this moment to say “I can’t do it!” in a comedy voice, and the whole routine grinds to a halt. “This is so . . . flipping difficult!” the choreographer says, with admirable, if camp, restraint.

Of course, it’s not merely puckish naughtiness that is making rehearsals for the show slow going. There is also the fact that the biggest dance show in Britain is being put on by a troupe of dancers, half of whom are not professional or, for want of a better term, are a bit crap. In just under two weeks of practice, celebrities – some of whom haven’t danced for three years – are supposed to come up to arena-tour standard.

“I can barely walk,” the predictably lovely Zoë Ball says, flopping down onto a chair. “My knees are gone. I’ll be in a wheelchair by the time we get to Newcastle. All the others are so young, I’m constantly seven steps behind. Norman [Cook, her husband, aka Fatboy Slim] says, if in doubt, do ‘jazz hands’, but I don’t think even I could pull off two solid hours of jazz hands.”

“ Strictly’s like childbirth,” the athlete Denise Lewis confirms. “You forget that it really, really hurt, and convince yourself you’re up for doing it again.” Given that Lewis is a superfit Olympic gold medallist, this is quite alarming. “I tore a hole in my knee live on TV last time I did it, but had to carry on smiling, in a sequinned dress,” she says. “And you get terrible floor burn when you do the spins.”

“I find it all quite easy, actually,” Di Angelo says, with leonine confidence. “I’m just going to come on, shout ‘Hello Wembley!’ and then have a laugh.” “But that’s because he’s been secretly practising!” Ball squawks, indignantly, later, when I tell her what he’s said. “In fact, they’re all secretly bloody swotting. That’s the thing, you see. We do all actually want it to be good. We really do.”

As the rehearsals recommence, it’s clear that this heartfelt desire is, as is so often the case, a mere adjunct to actual reality. While some do dance with the hips of a snake – in particular, it would take a blind, straight, dead man not to rejoice in the rousing insistence of Di Angelo’s pelvis – others do, sadly, dance with the hips of a hake. Darren Gough, in particular, looks like a large fridge/freezer being wheeled on a trolley out of Currys, and the semi-celebrity chef appears to be made of tin.

But then, this is the joy of Strictly Come Dancing. This is the point of it. This is what we want. We want a show of celebrity aunts, uncles, dads and sexy cousins joyfully giving it a bit, in silly trousers. We would be unmoved by anything less . . . utterly British.

Strictly Come Dancing Live! opens in Glasgow on Friday. Tour details www.strictlycomedancinglive.co.uk

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