Cue fire: a peep backstage at the National

The National Theatre is revealing the tricks of its trade. Rob Hastings reports

Creating a giant fireball is easy with a couple of canisters of propane gas and a bundle of hi-tech electrics to play with.

But it becomes somewhat harder when you have to do it in a tight space within a carefully constructed wooden set on the main stage of the Royal National Theatre.

There is the risk of burning down the building and incinerating the front row of the audience – not to mention the actors.

Contemplating the skills involved in putting together such pyrotechnical feats, the man nicknamed Mr Flamey-Flamey smiles wryly. "When you're working with someone like Jeremy Irons, you can't afford to singe his head too badly."

Paul Wanklin has been senior armourer at the National Theatre on London's South Bank for the past 10 years. While the theatre has long been the place to go for masterful performances of tightly nuanced drama, it's his job to ensure it also competes with the kind of high-octane spectacles more commonly seen on the big screen.

Yesterday he showed off his pyrotechnical and other special effects skills as part of "Discover", the theatre's half-term holiday programme of behind-the-scenes workshops.

Some children might yawn at the prospect of going to the theatre, but it's unlikely that anyone could nod off during any production that Wanklin is involved in. Before entering the Olivier auditorium yesterday, the children could barely conceal their delight as they were told to expect "lots of guns and swords and bangs and blood".

Cue stunning fireballs, exploding apples and deafening shotguns. Cheers of "Do it again!" and "More!" were never far behind – and then the children got to try out some of the equipment for themselves.

"The audience need to go 'Wow, how did they do that?'" says Wanklin. "That's what I like. We've even had people running out of the theatre!"

When he applied for the job via a newspaper advert, the Zimbabwean-born Wanklin could hardly have been a more appropriate choice. He had been in the army for eight years before becoming involved in special effects – he served in the Royal Electrical Mechanical Engineers – and he says he was only a small boy when he first began "blowing things up" for fun.

The tasks put before him can vary enormously, depending on what a production demands and how ambitious its director chooses to be.

"It comes straight from the director, what effects they want, so we work together very closely," he says. "They might say they want rain or fire or explosions, and then we have to work around the limitations of the physical space we have.

"My job is all about engineering. It's about making things that nobody else makes. You can't buy this stuff off the shelf."

Wanklin is currently working on making a pack of replica blood explode from the body of an actor at the moment the gun is fired at him. Another recent job was to project a fake snowball against a window and make it burst.

Special effects can be done relatively easily in the film business, with multiple takes, sound editing and CGI software. But in a live environment, Wanklin cannot afford any slip-ups.

"We've had guns fail to go off, but we've never had any accidents. We always try and have a plan B. If a gun doesn't go off, we always have one of the stage managers standing with a gun just offstage, so they can provide the noise of a shot themselves.

"Any piece of machinery fails sometimes," he says. "We've got so much radio-controlled stuff, smoke machines and radio mics, there's a lot of interference with signals."

One could imagine some of the more tentative, classical stage actors wondering what they have got themselves into at the prospect of all this commotion. But Wanklin, who has worked on films including Bond thriller Quantum of Solace, says it is surprisingly rare to experience such hesitancy.

"They can be wary, but that can be a good thing," he says. "They're generally good at training actors to work with effects these days, a lot of them are taught how to work with sword-fighting and guns and things at drama school. Before we ever fire anything, we take them through it step by step and show them what's going to happen.

"My biggest fear – and it does keep me awake at night – is simply: Can I do this? You don't want to set fire to the building or hurt someone. I just have to think about everything that could go wrong, and that's how I reduce risk."