Calum Best has never sung in public before. But he’s about to get plenty of practice.

The 34-year-old is deep in rehearsals for his first ever panto – Cinderella at the Epstein Theatre.

And as he’s proved through a series of appearances on TV, most recently Celebrity Big Brother, that he’s certainly up for the challenge.

“It’s about getting that first little bit out, you know?” he smiles after a 30-minute session with the show’s vocal coach.

“But I’ve said can we have as many duets as possible, so it’s not all the pressure on me!

“At the end of the day, I think people who are coming here to watch it will know that I’m not here to be some kind of performing singer from X Factor.”

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Luckily for Calum, there are plenty of other singers in the cast.

They include Any Dream Will Do’s Chris Barton as Dandini (“Chris is a great singer,” says Calum, “Earlier he was practising by himself, and I was thinking, God, I don’t want to have to follow that!”), and Liverpool’s own Beryl Marsden who is making her panto debut as the wand-waving Fairy Godmother.

Not forgetting Prince Charming’s love interest, Cinderella, played by Epstein panto regular Alison Crawford.

What makes the show, opening next week, even more of a step into the unknown is that Calum never experienced traditional panto as a child.

“They don’t have much panto in the States where I grew up,” he reveals. “It’s just something I’ve always heard about, about how the parents bring their children and everybody has a laugh and it’s all quite comical.

“But the funny thing is, I know it’s comical, but when you’re in it, here now, I think – wow this is actually quite serious because I’ve got to come and do a month’s worth of shows at x-amount of shows a day.”

Calum was born in California, a long way from his dad George Best’s own boyhood in East Belfast.

He was raised by him mum Angie in Los Angeles – as he says, not exactly a hotbed of pantomime – before moving to the UK when he was 21.

And while he may have become best-known as a model, and for making the headlines for various reasons (when he arrived in London “some madness happened” he smiles wryly), it turns out that when it comes to acting he’s actually not a complete novice.

“When I was 17 or 18, I went to a really prestigious acting class for two years,” Calum says.

“It’s just it was a path that I wanted to take at the time, you know? I was still young and I was trying to figure out what I wanted to do.”

What he did do was find himself on the carousel of reality TV shows like E4’s Fool Around With, and, memorably, two series of ITV’s Love Island, the first, in 2005, alongside Atomic Kitten’s Liz McClarnon.

He won the series in 2006 alongside Paul Gascoigne’s stepdaughter Bianca.

There was also Totally Calum Best – an MTV show on which he attempted to remain celibate for 50 days.

Calum Best does his best smoulder as Prince Charming in Cinderella at the Epstein

Earlier this year, he entered the Celebrity Big Brother house – alongside Liverpool’s Keith Chegwin among others – and ended up taking a very creditable third place.

“I hadn’t done TV for quite a few years,” Calum says. “I’d taken some time off to work on my health and work on me and just on different businesses.

“And I felt good, my health was good, I felt good all around really.

“Big Brother said – do you want to come and do it? And I hummed and hawed, because I’ve avoided reality TV for so many years.

“And then I thought, I’m a commercial entity realistically, and if I want people to know what I’m like at this point – and I did actually, I went through a few years of whatever, not the best of times, so I went and did Big Brother and it worked out really well for me.”

“It’s funny,” he muses, “how Big Brother led me to so many different things, as much as it’s car crash television.”

Menswear range Burton called to ask if he’d consider becoming the face of the brand.

“I like to think I’m a gentleman,” he says. “My mother raised me with good manners, and I think I got to show that on the show.

“Burton’s catchphrase is ‘a line for gentlemen’. And they’ve got me fronting that, so the fact is somebody had faith to say ‘we think you’re a gentleman’.”

He also got a role in a new film, titled Requiem, in which he plays a fallen angel.

Then there’s a new gym business venture with mum Angie, whom he describes warmly as “a very close friend of mine”.

Which brings us to Prince Charming in Liverpool.

It’s usually a ‘chilled’ Christmas for mum and son, and, he confirms, she will definitely be coming to see him strut his stuff on the Hanover Street stage.

“I’m actually terrified!” he laughs of the new challenge. “But excited.

“Terrified of the unknown, but I know as soon as I start that I’ll love it."

He adds: “I’m going to try and please all the fans that come. I can make fun of myself. I can make fun of others. It’s all good.

“I want to try and entertain the best I can.”

Cinderella is at the Epstein Theatre from December 10 to January 3.