He was The One That Got Away in the most notorious SAS mission of all time. Now giving careers advice in schools, Chris Ryan talks to Steve Pratt about life after the special forces.

The noise at the rear of the school hall made pupils spin round in their chairs, to find themselves face-to-face with a man in full SAS assault gear, carrying a machine gun and pistol. The initial shock turned to laughter when the intruder was revealed as their drama teacher.

Chris Ryan, the SAS man turned bestselling novelist, had achieved the desired effect of staging the stunt during a visit to a school in his native Newcastle. "It captures their imagination, and makes them ask questions," he explains.

"Kids are brilliant because they're not afraid to ask things, unlike some adults. Children can be very open and direct, and say, 'have you ever killed anyone?'. I tell them it's the dark side of being in the Army, and nothing to joke about or be proud of.

"I want to get over the message that in war there are no winners. A war might be a triumph but no one wins."

He knows people kill and get killed in action. Ryan's not proud of having killed, still suffering from nightmares. Part of the reason for quitting the SAS was the post-traumatic stress affecting him. He notes that, since the Falklands conflict more soldiers have committed suicide than were killed in the war.

The Gulf War was the arena for the incident that earned Ryan fame as The One That Got Away. He was part of the eight-strong Bravo Two Zero SAS team dropped behind Iraqi lines to destroy Scud missile launchers.

The mission went wrong from the start and ended in failure, with three men dead and four captured and tortured by the Iraqis. Only Ryan evaded capture, reaching safety in Syria after days walking across dangerous territory.

He's been touring schools to coincide with the debut of his new series of children's books, Alpha Force, about five youngsters forming an elite team to battle injustices in the world. The first two volumes, Survivor and Rat-Catcher, are published this summer.

A man who fought for a living may seem a strange person to offer children career advice, but his school visits serve a purpose other than army recruitment. The aim is to persuade pupils of the value of staying at school and the importance of getting an education before entering the big wide world.

Despite that message, Ryan has done well for himself after leaving school at 15 with the intention of joining the Army, only to become ill and miss the intake.

He became unofficially attached to the 23rd SAS Territorial Regiment, accompanying the recruiting team during the selection process. "They gave me a uniform and equipment, and treated me more like a mascot than anything," he recalls.

At 23, he applied to join the 22nd SAS Regiment in Hereford. "My image of being in the Army was running over the moors with a gun in your hand and going to foreign lands. The reality was staying in the classroom, learning different languages or about communications or bits of kit," he says over a drink in a York hotel before a promotional appearance at Borders bookstore.

Taking part in operations in Northern Ireland and Zaire led him to the conclusion that there are no winners in war. When he returned from the Bravo Two Zero failure, he felt he was fine and turned down the chance to talk to psychologists and psychiatrists.

Operating in Zaire, he found himself suffering from post-traumatic stress. This showed itself while attempting to retrieve vital documents from an embassy surrounded by a hostile mob. He lost his cool after discovering the documents weren't there after all.

"I wasn't panicking, I was frightened," he recalls. "I thought, 'we're going to be murdered here' and I must have frozen on the spot. The documents weren't there and we could all have been wiped out."

That incident helped shape his decision to quit the SAS in 1994. He also had what he calls "a bad freefall experience" and a realisation of the effect of what he was doing when a man he'd selected for the SAS became the first soldier to be killed in Bosnia.

"I decided to leave because I couldn't make the commitment. It's difficult because are you admitting to yourself you've lost your nerve and aren't prepared to give your life," he says.

Becoming a bestselling author happened by accident. Six months after leaving the Army, he was running a private security team when a bidding war for the rights to the Bravo Two Zero story, which SAS colleague Andy McNab turned into a book, broke out between TV companies. Ryan signed a contract for a TV movie called The One That Got Away.

His idea of a factual dramatisation was not reflected in the script, and he argued with the makers about the characterisations. "The film was something I wasn't proud of, and I was very disappointed," he says. When he published his own account, criticism of the TV movie was also directed - mistakenly, he believes - against his book.

More recently, he's been at loggerheads with Michael Asher, who made a Channel 4 documentary claiming to disprove the account of events given by McNab and Ryan. They were accused of embellishing the story in their books.

Ryan has expressed "contempt and disgust" at the accusations, issuing a challenge to Asher which roughly translates as "let's go outside and settle this man-to-man".

The matter still rankles, as mention of the row sparks off a lengthy point-by-point rebuttal of Asher's claims. Most hurtful were things Asher claimed about others in the patrol. "I still stand by everything I did," says Ryan.

He's written a series of bestselling novels, including The Watchman and now his seventh thriller Land Of Fire, a fictional take on the Argentine military junta's bid to reinvade the Falklands.

He's also created the ITV series Ultimate Force, which stars ex-EastEnder Ross Kemp as an SAS man operating in the UK, Northern Ireland and Bosnia.

The series will be screened this autumn, and Ryan is hopeful a second batch will be commissioned. He has a cameo role as someone who loses an argument with Kemp's character, although seems less than enamoured by an actor's life. "It's a strange old business to be in, very boring. You're on set for 12 hours and might only do one hour's work," he says.

Other books are screen-bound too. Columbia TriStar wants to turn his children's books into a TV series, and the film rights to The Watchman have been sold.

Ryan - who writes under a pseudonym - is planning a more permanent return to Tyneside. "I spent a lot of time there this past year because I lost my mum to cancer," he says. "I've looked at a couple of houses in Newcastle and my intention is to move back there."

* Chris Ryan's new novel, Land Of Fire, is published by Century, £16.99.

* Survivor and Rat-Catcher are published in the Alpha Force series, £3.99 each.