It must be hard being a dedicated Brad Pitt fan. You know your idol is in town but it doesn't make the slightest bit of difference - you still can't get anywhere near him.

In fact, he might just as well be lying in the arms of his new bride Jennifer Aniston in his southern California mansion rather than roughing it down the road at Oxford Prison.

In town: Brad PittThe Fight Club star is at the prison to film the opening scenes for his new film Spy Game.

Shooting started on Monday and will continue until Friday, by which time Pitt will be ready to leave Oxford behind him and move on to Hungary where the next scenes will be shot.

Passing the entrance of Oxford Prison it's easy to tell that something's afoot.

Security is tight - a combination of a private firm and Thames Valley Police - and paparazzi photographers are keeping a vigil, just in case they get an opportunity to take a snatch picture of Pitt on location.

A steady stream of fans has been keeping the photographers company as they wait patiently in the rain for a glimpse of their idol.

One 20-year-old fan, who was too embarrassed to be named, said: "I love Brad Pitt and all his films. I think my favourite is Fight Club because it's so action-packed.

"We've been waiting here for quite a while but I don't know if we'll get to see him. It would be amazing."

Rumours have been circulating all week about where the Hollywood superstar is staying.

The crew and cast are scattered across the city, staying in eight hotels. It has been rumoured that Pitt is staying at the Randolph Hotel, although many believe that is a red herring circulated to throw his fans off the trail.

Reports that he is staying at the Oxford Spires Four Pillars Hotel, in Abingdon Road, have been strongly denied by staff.

In the film, Pitt plays the part of a CIA agent alongside Robert Redford.

Redford's character has recruited Brad's to the CIA and sees him as his proteg. But during the course of the film he learns that Pitt has been arrested for espionage and is incarcerated in a Chinese prison.

The older and wiser CIA agent sees it as his duty to devise a plan to get Brad out.

Oxford Prison is being used as the backdrop for the scenes inside the jail which show Pitt in a prison cell.

Production publicist Patric Scott said: "The prison is a wonderful setting for us. It looks very worn and depressing. Our production designers have moved in to give it extra touches so it would be realistic.

"The scenes we are shooting play an integral part in the movie, providing the main sequence at the beginning."