The star interviewed Sinn Fein president Gerry Adams and Progressive Unionist Party leader David Ervine while making a documentary on the city's political murals.

Onlookers were surprised to see the familiar Hollywood face in front of a depiction of IRA hunger striker Kieran Doherty. "Vince Vaughn was really friendly, really open," one told BBC News. "He talked to the locals, signed autographs and had a bit of a craic with them. He seemed really interested in the murals."

Ervine, who met the star in the east of the city, said Vaughn became interested in the murals on a previous visit. He commented: "We did a spot of filming in Dee Street around a mural depicting people coming to the shipyards.

"I was explaining to him that years ago we would not have a mural like this because it would all have been about politics and our divisions. I told him that, for me, the mural was the epitome of the change process that is going on in Northern Ireland. The murals are changing.

"He was taking a break from shooting a film in London with Kevin Spacey to do this documentary and came over for this weekend. There's no question he's genuinely interested in the subject.

"He was telling me his interest was sparked on a previous visit when he took a black taxi tour from the Europa Hotel. He knew nothing about the murals before that trip."