In a factory unit on Osney Mead, an exotic creature was being displayed on a computer screen. “He’s ten feet tall, with one eye. He looks like an enormous, slightly uglier Shrek — or like that Russian boxer, Nicolai Valuev, only even bigger.”

The description comes from actor Richard Stacey. The day before we met, he’d been to see the real thing — the Giant’s costume, which he will wear in this year’s Oxford Playhouse pantomime, Jack and the Beanstalk.

“ It’s amazing,” Richard continued. “His hands work, and he’s been made by two people, one of whom used to work for Jim Henson on The Muppets. He also did the original Star Wars, so I spent a lot of time asking him about Yoda! The costume is quite heavy, it’s got a frame inside that sits on you.”

The factory unit had been taken over as a panto rehearsal studio, and when I arrived proceedings were in full swing.

“Lay it on thick!” called director Peter Duncan, a veteran of three previous Playhouse pantos. The scene was the one in which Jack has sold Buttercup the Cow to the evil Fleshcreepy for a bag of gold. Jack’s mother, Dame Trott, lets fly at her son — the bag of gold was a fraud, containing only worthless beans.

“He’s just too innocent,” said Chris Carswell, who plays Jack. “He’s the nice guy who trusts everyone. He’s not that dim, but he’s not entirely bright either. He gets fooled by the wily Fleshcreepy too easily, bless him. He’s got a heart of gold, and believes he’s done well for his old mum, but sadly he hasn’t.”

As the rehearsal proceeded, I was handed a piece of programme copy. Alan French, playing Dame Trott, had written about “the joys of flouncing in frills”.

“I don’t remember writing that!” Alan protested, as gales of laughter erupted from his fellow cast members. “I didn’t originally realise it was a skill to flounce, I thought anybody could do it. But, of course, I have been likened many times to Judi Dench, who is the world’s most famous flouncer in frills.”

I wondered how Alan first got into the honourable profession of playing panto dame.

“It all started many years ago, when I played Prince Charming roles.” (More laughter erupted at this revelation.) “Then I didn’t do panto for a long time, but about six years ago, my agent phoned and said, ‘how do you fancy Cinderella in Preston, love?’. I said, ‘oh right, Prince Charming?’. And she replied, ‘I think you’re a bit old for that now, they want to see you for Dame’. So it was a baptism by fire — and do you know what, it was so much more fun than playing Prince Charming! Subsequently I’ve terrorised four Cinderellas as an Ugly Sister.”

Appropriately enough, Cinderella was the first panto Alan ever saw.

“I was taken to see it at the Royal Theatre in Northampton when I was nine. I was completely blown away by it. I know everybody says this, but I literally sat there thinking, ‘I want to do that’.”

In an adjoining room, the costume department was hard at work, and Laura Pitt-Pulford, playing Jack’s romantic interest Jill, emerged from a fitting.

“Costumes are always a worry, because that’s what you’re going to be seen in for the next couple of months. I asked if I could have a pair of skinny jeans and a tank top, but they said no! But seriously, I’m very happy, I’m going to look very princess-like — every little girl’s dream.

“Jill is quite strong-willed — she’s the squire’s daughter, but doesn’t like to think that she’s a toff. But she falls in love with Jack, and he’s a bit, err, common. Daddy gets very angry, but Dame Trott is a big softy about it.

“I’ve chosen not to play Jill as a girlie-girlie type, running around skipping. I’ve made her a bit of a tough cookie — slightly geeky. You see Jack and Jill fall in love right from the beginning, it’s very romantic. And they do get to kiss.”

Tomorrow, the Playhouse’s Jack and the Beanstalk will be unveiled for the first time. For actor Richard Stacey it’s a crunch moment.

“The danger is that you think, ‘that’s not funny any more’, because you’ve heard a joke a million times in rehearsal. But the second you bounce it out in front of an audience, you discover it was funny all along.”

Jack and the Beanstalk opens tomorrow at the Oxford Playhouse, and continues until Sunday, January 17. Tickets at 01865 305305 or online at oxfordplayhouse.com