He may have served with the SAS for 10 years and faced things most people couldn’t imagine, but Chris Ryan said his biggest fear was facing a queue of people at a book signing.

The soldier-turned-author will confront his nightmare in Canary Wharf on Monday, September 7, as part of promotion tour for his latest novel Hellfire.

He said: “When I’m behind that desk and my head is down, I have no awareness of who’s around me and all these eyes on me.

“I come out of there with a dry mouth and really sweaty palms – it’s such an alien situation to me.”

Fortunately he’s unlikely to come across his other big fear – MRI machines – on the tour but it seems curious he’d be phased by anything much after managing to escape across Iraq during an operation in the First Gulf War.

The experience inspired his first novel, The One The Got Away, published in 1995 and he has now sold four million books worldwide offering a real-life perspective on what happens on the front line.

Hellfire by Chris Ryan

He talks candidly about his experiences, including the guilt he felt when his first SAS student died and admitting he was a “horrible” person when he first returned from years of service and suffering Post Traumatic Stress Disorder (PTSD).

Talking of his student he said: “I kept questioning whether if I’d been a bit tougher, he would have been able to make it. That was really when I started thinking I should leave.”

This is after serving in overt and covert operations and also as sniper team commander of the anti-terrorist unit during the Gulf War.

He said: “I wasn’t a very nice person at all after coming out of the army, but that was part of the process of moving on.

“Initially when I started my novels I think they could have been seen as a bit of a healing process and they affected me a lot more.

Chris Ryan in his SAS days

“Now I have got to a point where I can write from a third person perspective.

“The help for soldiers with PTSD is much better now – in my day there wasn’t anything – apart from the families officer, who had the same amount of sympathy as a rat.

“One time I was in with him and he had a family there who had just lost their son.

“The man’s tombstone was in the office and the family saw the wrong dates of his death, leading them to think he had died in different circumstances and they had been lied to.

“When they left the families officer just said he thought they were ungrateful as they had been bought a gravestone and hadn’t had to pay for it.”

On Hellfire, which features scenes reminiscent of Isis brutality in Syria, Chris says years of experience have given him the ability to create stories that seem close to real life.

Chris Ryan at a previous Waterstones signing in Captain Cook Square

He said: “When you are in this environment for so long though, you can get a feel for what might happen.

“When you create a book you have to start it about a year before it is released, so I have to rely on my experience and knowledge to create a story as close to life as possible.”

Chris’ passion off the back of his novels is helping children learn through reading and talking about his experiences, although it’s not always an easy ride.

He said: “I went to a school in Leeds where I walked into a hall with 350 kids that had no interest in listening. They were shouting and swearing regularly without any reprimand.

“I got to the point during my talk where I was about to leave – but I’m really glad I didn’t.

“At the end this small group of about 15 who had started a reading and writing group came up to talk to me. If I had left when I wanted they would have gone away so disillusioned.”

Chris will be at Waterstones in Jubilee Place Mall from 1pm on Monday.

Go to chrisryanadventures.co.uk for more information about his work.