Some celluloid images stay with you forever. An ageing John Wayne mowing down opponents in True Grit. Big Indian Chief picking up a water fountain and throwing it through a window in One Flew Over the Cuckoo’s Nest. Lee Marvin spraying bullets into an empty bed in Point Blank. In comedy I’d pick two scenes: Jack Lemmon in drag, dancing with Joe E Brown in Some Like It Hot, and a low-budget British film featuring a stammerer, trussed up like a turkey, desperately trying to say the immortal words "Cathcart Towers Hotel".

The British film in question was A Fish Called Wanda and the stammerer was played by Michael Palin. I saw the film on its release in 1988, aged 21. As a fellow stammerer I was unsure whether I would be amused. But I was curious in that ever so slightly uneasy way when you know your affliction is depicted – eyes and ears on tenterhooks. And, much to my surprise, I found myself laughing out loud throughout most of the movie.

And, of course, the man who played K-K-K-Ken, the speech-challenged bank robber, animal rights activist and victim of Kevin Cline’s cruel tongue was Michael Palin, a legend of Monty Python and player in some of the funniest sketches on TV. Now he’s perhaps even more famous as a global traveller. A curious man armed with just a notebook and blackcurrant fruit pastilles, he has now visited 94 countries. Not bad for a humble lad from Sheffield who’d never been anywhere until his twenties.

Palin’s gift as a comedy actor has always been for a kind of guileless, faintly simpleton-like innocence. Revisit The Dead Parrot sketch, the Lumberjack Song and – his own favourite – the fish-slapping dance with Cleese, and you’re struck by his unique facial expressions. Like the great comics you just look at him and start laughing.

In the flesh, however (we meet at a hotel in Sofia where Palin is being feted by the Sofia Film Festival), Palin comes across as serious and impassioned. Slim and fit for a 65-year-old, his face is lined and reddish with the slightly rugged, sunburnt look of the seasoned traveller.

Perhaps Palin’s best known film role remains Wanda. "My father had a very bad stammer, and I never quite knew what it was all about," he says. "In those days you didn’t discuss it; you just accepted it and that was it. And then John [Cleese] asked me, long after my father had died, to play in a movie where the stammerer had to reveal important information at a particularly vital moment. I told John that it was essential to make the stammer sound right."

Palin certainly understood the psychology of stammering, namely that pleasantries – except for extremely severe stammerers – come easy, but imparting crucial words, particularly to an expectant audience, is altogether more tortuous. Following the movie, Palin set up the Michael Palin Centre for stammering children in London and has taken a keen interest in the subject ever since.

The film was a massive hit, earning Palin a best-supporting actor Bafta. By this time, of course, he was already famous from the Python sketches.

From a humble home, Palin studied at Oxford, where he met Terry Jones, with whom he performed in the Oxford Revue. Later, as a professional, he joined the Frost Report (a satirical programme of the day featuring the now legendary David Frost) alongside Cleese. He never dreamt of becoming a film star, let alone a record-breaking voyager. The modest man in front of me still doesn’t quite believe his luck. He blushes when another interviewer refers to him as "a national institution".

As a youngster his comedic influences were Laurel and Hardy and the Goons’ radio show (Spike Milligan, Michael Bentine, Peter Sellers and Harry Secombe) – whose anarchic humour was a kind of precursor to the Pythons. He also loved the early Woody Allen movies. Away from comedy, his screen idols were James Dean, Montgomery Clift and Marlon Brando. When the Pythons formed in the late 60s, he and Cleese, Terry Jones, Terry Gilliam, Eric Idle and the late Graham Chapman performed 45 episodes of classic television comedy followed by several feature length movies. His favourite Python film was the Life of Brian, in which he played a succession of characters, including Pontius Pilate.

When pressed, Palin names two particular "geniuses" in the Python team. "Cleese because of the intensity of his performances, his towering size and sheer comic energy. He was incomparable. And Terry Gilliam. He had a tremendously fresh, original and inventive graphic sense that all the rest of us lacked. His talent was enormous, taking us from on sketch to another with wonderfully confident artistry. John’s acting and Terry’s graphics were incredible. But John’s contribution as a writer was enormous, too."

He thinks that today’s humour is becoming coarser. "You get wonderful comedies like The Office that don’t rely so much on aggression for its humour. It just plays on situation and observation," he says. But he’s critical of presenters like Jonathan Ross. "I think his radio show is extremely good – with his flights of fancy – but his TV show has become too laddish. It’s just like a bunch of blokes together talking about getting a few birds. Personally, I don’t find this very funny. I don’t think swearing is particularly funny, either. The best humour is something that catches you unawares. As soon as something becomes a cliche I lose interest and swearing has become a cliche. There’s still a lot of good stuff out there. It’s just that there’s a kind of fear of losing the youth audience."

Traveller’s tales
Palin’s travels, now featured on his extensive website, have created a kind of second wave of fame for him. He came to Bulgaria a couple of years ago, visiting, among other places, Plovdiv’s Gypsy quarters, Rila Monastery and Rhodope Mountain. He also interviewed Bulgarian pop star Aziz. It was in about 1992 that the BBC first approached him to do a travel series, an offer declined by three others before Palin accepted.

None of the series are vehicles for Palin’s ego. He shows a real interest in the people he meets and he melts in, chameleon-like. He’s not condescending, he never gives an impression of "slumming it" and so people open up to him. Unlike previous British globetrotters – Clive James or Alan Whicker, for example – he never dwarfs the subject or the location. Few people are so well travelled, certainly not politicians. So Palin is perhaps uniquely well placed to comment on what seems an increasingly polarised world.

"We’re all human beings who live and share this planet. No one is more powerful than anyone else anymore," he says. "People with very little power in one corner of the globe can cause mayhem in another. That’s why it’s so important to talk and listen to other people. If we can’t do that now, after thousands of years of wars, if we can’t learn lessons and avoid rushing into a conflict, then we’ve failed. We should try and understand the other side and do whatever we can to avoid having to kill somebody to make our point."

Should this stretch to organisations like Al-Qaeda? "We have to learn why they are doing what they are doing, and I think to regard it as a purely lunatic organisation of thugs and totally unprincipled killers is to miss a lot of points," he says. "So to find out why they do what they do and what they believe is very important."

Palin joins a long list of people queuing up to denounce what he calls ‘the Bush doctrine’. "If you say you shouldn’t talk to your enemies on the basis that you’re just giving in to them, you learn nothing. And you end up using violent methods that only strengthen the people you won’t talk to. It’s just not good psychology. I’m not saying that just by talking you have to give up what you believe but I think that, if your own position is strong, you can talk to anyone."

Neither does he believe in the clash of civilisations thesis, that the West is hated by poorer parts of the world. "I’ve encountered very little anti-Western feeling, although I wouldn’t say I’ve been to all the hotspots of the world. In 2003 we did go to the New Frontier – the Khyber pass – and maybe there were people there who resented our presence. But, if they did, they didn’t come forward and make it clear to us. Many people we spoke to were very interested, perhaps because we just came to listen. We didn’t come with guns and we weren’t there as investigative journalists. We were just soaking in the landscape. In a sense they were quite naive but intrigued, and very keen to share their opinions with us."

Palin’s gentle manner helps. "I think it’s all down to how you approach people. If you approach as a sort of very rich outsider with many more advantages than them – just being curious and wanting to take their pictures – then it won’t work. You’ve got to go into their tents, spend some time drinking tea with them. Then, gradually, you realise that they may hate your government but they don’t hate you personally. Certain things are universal, love of country, children and local pride."

In showbusiness, where relationships are notoriously short-lived, Palin has defied the trend by being married to his wife Helen for more than 40 years. Perhaps his success and popularity is down to the fact that he’s never allowed his own ego to get too over-sized. Scrach the surface and he’s still a shy young boy from Sheffield, curious about the world and more interested in listening than lecturing.