WHEN all hell breaks loose in a dramatic riot in the latest Jason Bourne movie most viewers will not know there is an Oxfordshire man behind the on-screen violence.

Former paratrooper Paul Biddiss spent last summer in Tenerife training Spanish extras to act as riot police in Jason Bourne, the fifth film in the Bourne series.

The married dad-of-five from Witney also worked with the film's star Matt Damon, with the pair spending time in the gym together during filming.

Mr Biddiss, who served in the Parachute Regiment for 24 years before leaving as a sergeant in December 2012, began his career in film after giving advice to George Clooney for a battle scene in The Monuments Men.

Most recently he was recruited for Jason Bourne to provide expertise on riots in Greece.

The Witney resident said: "I had to co-ordinate the riot and give advice on what guys were doing in different situations.

"The extras played the role perfectly.

"There was a write-up of the film in the Los Angeles Times from a journalist who had been in the Greek riots and he said it was the most realistic depiction he had seen on the big screen.

"I have been involved in riots in Northern Ireland and that is what I was able to bring into it."

Before heading to work on Jason Bourne Mr Biddiss had worked on BBC One's historical drama War and Peace, which aired at the start of the year.

He said his attention to detail allowed him to make the switch from the Napoleonic era to modern times.

The 47-year-old said: "It is 60 per cent research and the remainder is your own experience.

"I did my research on the Greek riots, both the riot police and the riots themselves.

"You build it up from a very simple lesson in how to conduct something and learning some Greek phrases to putting the full riots on.

"It can be tricky though, I have just finished another film called the Death of Stalin.

"Sometimes the Government wants to keep things secret and that makes research more difficult."

Mr Biddiss has also worked on Mission Impossible Rogue Nation and Second World War action drama Fury, which featured Brad Pitt.

He is currently working on superhero film Justice League which is due for release next year.

He said: "When you are training people who have a different language you have to get your information across.

"But after two or three days they know what I am after and I can train them.

"They are all from an extras company and they go to a psychological assessment because we cannot afford someone to just go off on one during a riot scene."

So far Mr Biddiss' time as a military advisor has seen him work with Hollywood stars and travel the globe working on some of the biggest box office blockbusters.

But in spite of his success he has no desire to get in front of the camera.

He said: "They wanted me to be in Jason Bourne but I said no.

"I do not enjoy that side of it, it is better not to.

"You need to be on the director's shoulders."