The X-Men star said: “I know there’s a lot of cynicism that surrounds celebrity endorsements, but I don’t look on this remotely as a celebrity endorsement.
“It just happens that I am an alleged celebrity, but I would be doing this anyway. I’ve had an association with the Labour party since I was campaigning as a five-year-old in the first post-war General Election.”
Mr Stewart said he had offered to help the party out in any way he could while he is performing in Chichester, but revealed he hadn’t been asked to pass on any tips for Gordon Brown’s TV debate appearances.
“I would have certainly made myself available if asked,” he said.
“I did, in 2000, have a conversation with Al Gore about a certain aspect of the style of presentation. He was kind enough to say last year that if he had paid more attention to the tips that I was giving him he might have been President, which I think was a small exaggeration.”
Kate Bartlett, who works at the university’s UK student recruitment and outreach department, was one of those who spoke to him during a meet-and-greet session.
She said: “We talked about the leadership debates and whether they’re a good thing or a bad thing, and the performances – he thought David Cameron had an act going.”
Dr Whitehead said he was delighted the star had visited the city.
He said: “He’s one of the country’s greatest actors, and for him to take the time to come and endorse what we’re doing in Southampton is marvellous.
“It’s far more than just a celebrity hanging his name on a campaign, this is truly what Patrick feels about the future of the country and that’s why he’s doing what he’s doing.”