Brad Pitt & Angelina Jolie's Former Bodyguard Claims He 'Basically Fathered' The Kids

                                             Opening up: Mark Billingham - pictured middle 

A man who worked as a bodyguard for Brad Pitt and Angelina Jolie for a year-and-a-half opens up about the estranged couple's fear their kids would be kidnapped and held for ransom, and much more, in an insightful new interview.

Mark Billingham, a decorated ex-member of the British Army, spoke with The Sun on some of the the eyebrow-raising anecdotes he picked up in nearly 18 months as head of security for the Mr. & Mrs. Smith stars and their six kids.

Among them include the painstaking measures they took to ensure their brood was safe, and the numerous run-ins with stalkers of the former king and queen of the A-list.

'The biggest concern for them was the kidnapping of the kids, it’s all about money,' Billingham told the paper of the couple's laser-focus on protecting the six children - Maddox, 15, Pax, 12, Zahara, 11, Shiloh, 10, and twins Vivienne and Knox, eight.

Billingham said that the Pitt, 52, and Jolie, 41, 'trusted [him] with the kids,' so much so that as he bonded with the celeb clan, he 'could take the kids anywhere [he] wanted to on [his] own.'

He also said that the former power couple were constantly uneasy about who would go near their children, to the point that they were mindful of security professionals when the occasion called for it.

'Even when I wanted to bring in extra people, they wouldn’t let any of those near the kids,' he said to The Sun. The

added guards 'could look out for them from a distance but they couldn’t physically touch them.'

Billingham spent so much time around the kids, he said he felt like he 'fathered them, basically.'