There's no limit to the special effects that little animated pixels can bring to the screen - but there's definitely something different and special about a live, on-stage show.

Especially one like Shrek the Musical, where familiar characters, including nursery-time favourites, step out of the animation frame into the best 3D of all: an all-singing, all-dancing cast of talented performers.

Dean Chisnall, the man who knows the big green Ogre inside out - he first played him in 2011 - reckons, however, that simply describing Shrek the Musical as a kid's show misses the mark. "If it's a kid's show, then that's only because the adults watching it become like kids themselves - they get the clever bits of humour, especially the Lord Farquaad comedy, that goes over the kids' heads.

"It's not offensive, just not the kind of 'funny' youngsters get. You can tell, from the stage, who's laughing at what. I just love it when the dads are in, usually on a Saturday matinee. They've come, because it's the family - but you can hear them, just howling with laughter. Mums are giggling. The kids are excited. And I really, really love the feeling you get - that everyone's having a good time, and that a lot of the pleasure they get is down to Shrek, down to you."

Listening to him enthuse, it's soon apparent that he's not giving routine lip service to the production, or those who cast him, when he says Shrek is his dream role. "It's a big, big role. It doesn't get much bigger, does it?" He laughs. It's true on various levels, for once he's in the full kit and caboodle of the character, he not only dominates the stage - he's the mainstay of the story and the show. How come a big lad from a small market town - Chisnall is 6�² 1�³ tall, and hails from Ormskirk in Lancashire - landed this Ogre-tastic role in the first place?

The first Shrek film had just launched in the UK when the 18 year old Chisnall headed to London and the Arts Educational Schools there. Shrek the Musical didn't exist at the time, nor, according to Chisnall, did his hometown have the kind of training opportunities he'd set his sights on

"I think my family did wonder - was this the right thing for me? I really had no idea why I wanted to be an actor, or be in musicals. I just knew I had to take that plunge into the unknown." Since then, he's found himself taking the plunge over, and over as career opportunities and fresh challenges have come his way, Shrek among them. Chisnall had been part of the ensemble in the original West End production, understudying the then lead, Nigel Lindsay, and wondering when - if - his chance to go green would ever come. It did, with added drama.

Five minutes into an evening performance, the fire alarm went off. While the theatre was emptying, Lindsay announced that his throat was bad and his voice was going. Half an hour or so later, Chisnall was Shrek-ed up and on-stage. The whole costume and make-up crew had gone full out to transform him in minutes rather than hours. In early 2012, Chisnall stepped into the Shrek fat-suit in his own right. Even after the London run ended, his life with Shrek continued: he headed up the touring production that come to the King's Theatre in Glasgow next week.

Nowadays, his full pre-performance make-over takes much longer than that manic 25 minutes of slap'n'go against the clock. "We reckon on the make-up alone taking about 2 hours," says Chisnall. "I just try to zone out, in my chair, and let them get on with it." He's referring to the slow, meticulous process of applying Shrek's face over his own features, using prosthetic pieces of silicon and latex that cost around £300 per show. If Chisnall can watch himself in the mirror, morphing into a big chinned, bulbous-nosed green ogre, it's when he's installed inside the fat suit - complete with platform-soled boots - that the full weight of being Shrek literally comes to bear on him.

"It is a very heavy costume," he says, cheerfully. "Until you get used to it, it all feels a little claustrophobic - and you have to re-think how you move about, it's so enormous. And it gets very, very hot inside it - it's like my very own personal, portable sauna - and I sweat. A lot. During a performance, I can drink seven or eight litres of water to keep from getting dehydrated."

Doesn't it get, erhm, rather ripe and whiffy?

"It's machine washable," says Chisnall, clearly enjoying the effect this image has. "It dries pretty quickly, so there's always one in the wash and one for me to wear. They don't seem to shrink - I lose the pounds, it's better than a gym membership."

For Perth-born Jen Raith, a company manager on the current tour, what Chisnall is describing with a chuckle is just part of what she calls "the other show".

"That's the one we do backstage, in order to make sure that what the audience sees out front is how it should be: magical."

As Raith walks me past rails of carefully arranged costumes, wigs, masks and a thirty-foot dragon-cum-puppet, she explains how the whole priority, backstage, is to live up to audience expectations, wherever they tour. "Every venue is a different set up, but it's our responsibility to make sure that the show still has the same production values as the West End original. Can anyone in the audience see the fingernail ridges on Shrek's hands? No way. But those details have to be there, for it to feel right - for the cast, too. We've already worked out how it's going to fit on-stage at the King's in Glasgow, so as the cast can feel totally at home, not to have to worry about quick changes, or props."

Chisnall, meanwhile, is wondering if it's worth bringing his beloved golf clubs with him.

"There are really good courses on hand, but somehow I think my time will be taken up getting into Shrek-mode. Why do I still enjoy it? Because Shrek isn't an ogre on the inside. He's a sensitive soul, capable of love and courage, even if no-one sees that. And every night, when I sing 'Who I'd Be', and it's really him opening up his soul, reaching out and touching audiences, I think how lucky I am to be Shrek in a show that people love."

Shrek the Musical plays at King's Glasgow from April 29 to May 17

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