Mark Billingham spent 27 years in the SAS, fought in Iraq and won the Queen’s Commendation for Bravery after capturing an IRA sniper by using himself as bait.
But his toughest gig was not on the battlefield — it was guarding estranged Hollywood couple Brad Pitt and Angelina Jolie.
Mark, known by his nickname Billy, was their eyes and ears for 18 months and became so close to their children he reckons he was their unofficial father.
Now he is entering the world of showbiz as a new instructor for the UK Channel 4’s "SAS: Who Dares Wins," which is back tonight.
He joins Anthony Middleton, Jason Fox and Matthew Ollerton to put 25 civilians through an SAS selection test in the Ecuadorian jungle.
It’s not for the faint-hearted, and one thing is for certain: Brad Pitt should not apply.
Billy, 51, says: “Brad wouldn’t last long because he wouldn’t have any cream to put on his face.
“It would be too sweaty and uncomfortable for him. He’s too pretty!
“But Angie could do it. She’d probably be the only one with balls at the end. She would stick it out.”
Channel 4 signed Billy after being impressed by his credentials.
His depth of experience also landed him the gig with Brangelina.
Billy admits: “I was Brad and Angelina’s head of security. The military set me up perfectly for what I did with them.
“The biggest concern for them was the kidnapping of the kids, it’s all about money.”
Working with the Hollywood stars meant Billy grew close to the couple’s six children — Maddox, Pax, Zahara, Shiloh, Knox and Vivienne — and he was one of the few staff members they trusted to be around the family.
He recalls: “Angie and Brad are very worried about who goes near their children.
“It was clear from the start we had a great chemistry and they trusted me with the kids.
“We got very close, I was living with them all the time.
“I could take the kids anywhere I wanted to on my own. No one else was allowed to do that.
“Even when I wanted to bring in extra people, they wouldn’t let any of those near the kids.
“They could look out for them from a distance but they couldn’t physically touch them.
“I took them swimming. I fathered them, basically.”
Stalkers were another big issue for the A-listers.
Billy recalls one particularly hairy incident involving Angelina.
He explains: “We had stalkers in Chicago and New York which I had to deal with.
“Angie was filming in a crowd and everyone’s got smiles on their faces except for one guy. He looked angry.
“A few days later we were coming off set and this guy came running down the road with photos to be signed.
“Angie wanted to get out of the vehicle and do it but I said no.
“I went and got the photos and took them to her. She was like, ‘Wow, these are personal photos’.
“The guy ran off then reappeared days later near the hotel, so I got him arrested.
“He’d been following Angie all over the States.
“To me, it was a John Lennon classic. Whenever she was on her own in pictures, he was smiling
“Then whenever she was with Brad, he had this angry look on his face.”
Billy reveals he was more worried about people attacking Brad than Angelina, saying: “People love her but hate him."