Alan Whicker: He's an icon, the person we'd most like to sit next to on a plane. He changed the way we think about holidays. So why is Alan Whicker up to his neck in sand?

Alan Whicker is in a deep hole, buried up to his waist in sand and with his head protruding from a plastic beer-cooler, like a jack-in-the-box with spectacles and a club tie. He is supposed to be in beach paradise, but the clouds have darkened, the cold wind is driving angry breakers against the shore and heavy rain is pouring down upon one of the most instantly recognisable heads in television.

The iconic travel presenter finds himself in this extraordinary position because he has agreed to film a series of television commercials for a travel website. After half an hour of wind, rain and unsuccessful takes, Whicker is still in his hole, getting colder and wetter than the drinks stashed around him in the ice-box. Yet he is wholly unperturbed by the hostile elements, urging his camera crew onwards with three short words: "Stiff upper lip!"

At 78 years old, and with 46 years' experience in front of the camera, Whicker surely doesn't need to be putting himself through all this just to record two words: "Hello Australia!" But he stays until the job is done, emerging from the sandy bunker in his signature blazer to a burst of applause from his young colleagues. "The consummate professional," purrs one admirer.

Broadcaster, author, traveller, war correspondent and soldier with the Eighth Army, Alan Whicker is one of the great chroniclers of the 20th century. He has reported on war in Korea and revolution in Egypt. He has engaged with the mudmen of Papua New Guinea and the Pocomanian sect of the Jamaican shanties, and ventured into numerous other distant cultures that were almost beyond the imagination of much of his audience. He has enticed some of the most elusive of interviewees, from the reclusive billionaire John Paul Getty and the Sultan of Brunei to the tyrannical Haitian dictator Dr François "Papa Doc" Duvalier.

On consideration, a few grains of sand and some drops of rain were never going to worry a man who has stood patiently at the side of a railway track in the Alaskan wilderness, a lone figure waiting to flag down a passing train, just for the benefit of a camera.

Whicker does have one phobia. "The bugs are the things that get to you," he says. "We know all about midges in Scotland, but the bugs in northern Australia are something else." But he cannot imagine a situation so uncomfortable that he might be moved to walk off set. "It wouldn't even enter my head," he says. "I'm an itinerant journeyman; I'm very happy to report from anywhere about anything."

After being buried and soaked on the beach, Whicker is up and filming again the next morning. This time he is clambering into the back of a giant basket so that he can be carried through a vineyard on the back of a hulking peasant farmer.

Part of the script requires him to use his unmistakable deadpan delivery to utter the words of a Queen rock anthem. "Don't stop me now 'cause I'm having a good time," drones Whicker. "I'm having a ball. Don't stop me now... Two hundred degrees, that's why they call me Mr Fahrenheit, I'm travelling at the speed of light..."

He is hoping that the commercials, for the web portal Travelocity.co.uk, will have a similar impact to his famous campaign for Barclaycard in the Eighties, which still causes people to stop him in the street, quoting the catchphrase: "Unlike some charge cards I could mention."

His willingness to send himself up shows that in spite of his early background as a hard-nosed correspondent, he has never taken himself too seriously and wants to be known for a sense of fun. "I think it does everyone a little bit of good. One doesn't stand on one's dignity," he says. "A lot of our programmes have been very light-hearted. They have been happy programmes - that's the intention. The main thing is always interest; you can do anything in television provided you're not boring."

Swiss Toni, the dapper and carefully-coiffured star of the BBC's The Fast Show, with his love of fine wines, fine cars and fine women, must surely have been inspired by Whicker, who was the first behind the scenes at Miss World and has had a long love-affair with the Bentley Continental. Entertaining in his hotel suite after the completion of his shoot, he appears a little disappointed that his offer to crack open a bottle of champagne at 11am is not taken up.

Whicker is charming to a fault, but he instantly rejects the suggestion by one commentator that he is the "walking epitome of Englishness". "Oh no," he says. "That's not something I would have said. One may come across as British, but it is not a considered method of living. One behaves as I believe one does off screen. I just do what comes naturally."

Alan Donald Whicker was born in Cairo in 1925, and returned from Egypt when he was a small boy to live in Hampstead, north London, with his mother after his father, a professional soldier, died from rheumatic fever. He was educated at Haberdashers' Aske's School in London, and then became a captain in the Devonshire regiment.

His interest in journalism developed after he was appointed the director of the Film and Photo Unit of the British Eighth Army as it advanced through Italy at the end of the Second World War. His experiences as a young soldier are a key to understanding the unflappable, even fearless, television personality that was later to emerge.

He has recently returned to the battlefields of his youth to make Whicker's War for Channel 4, which will be shown in the new year. "It was a great joy for me to go back and see where we had been and where my friends had been and where some of them died," he says. "The very houses that we were living in or the ditches that we had slept in. It made one very grateful to be alive, to have lived through that kind of experience, where so many died."

Whicker said that he had experienced the Anzio bridgehead and other hostilities "in an unalarmed state". "One didn't like it much, but one was always realistic about it. I don't remember being frightened at any time. Worried, perhaps, one was a bit, but - however dangerous it was - it was more stimulating than fearful."

Ever since, he has retained a sense of calm detachment in the face of danger, seeing himself as a neutral observer: "Don't shoot, I'm not fighting, just watching." The loss of friends at a young age has also given him a sense of fatalism. "[War] taught you. You realised how important luck was. Luck is all. Luck is everything."

Whicker would be the first to admit that he has been the recipient of great good fortune, enjoying a career that has helped him to top polls as the "ideal guest" at fantasy dinner parties, and as the person whom travel-agency clients would most like to sit next to on a plane.

After the war, he began working as a foreign correspondent in the Far East, covering the conflict in Korea and then joining the BBC in 1957. His first film, in black and white, was about the problems faced by landladies in Ramsgate, but he soon established himself as a more geographically adventurous correspondent for the flagship current-affairs showTonight.

Within two years of joining the corporation, he had his own show, Whicker's World, which took him on a journey of more than a million miles, spanning five decades and generating hundreds of programmes. At its height, the show beat Coronation Street in the ratings. It is still being screened on digital channels. Whicker was given the Bafta Dimbleby Award in 1978 and was incorporated into the Royal Television Society's Hall of Fame in 1993.

He became such a familiar face on television that one woman wrote to him to ask if he liked her curtains. A group of fans formed the Alan Whicker Appreciation Society, and dress up as him. The Monty Python team produced a sketch located on a mythical Whicker Island, populated by a colony of lookalikes who were reported to be in jeopardy from the declining number of "rich people left to interview". It also mocked his love of alliteration - "waterfalls of whisky wash away the worries of a world-weary Whicker..." Whicker claims to have enjoyed the joke. "The fact that Monty Python went out of its way to take the mickey out of me, I prefer to regard as an accolade."

The travel presenter had further insight into just how far he had come when he attended an awards dinner recently and found himself rebuked by a senior female television executive. "She reprimanded me for some programme that she didn't think was worthy of me," he recalls. "She said, 'You're a fucking icon.'"

Whicker, who says he briefly considered that description as a possible title for his next piece of autobiography, has throughout his career built up this iconic status by developing the Whicker brand (unconsciously, he says). As well as programmes such as Whicker!, Whicker's World and Whicker's War, he has named his unique way of talking as "Whickeric" (the emphasis, he says, is on the second syllable).

When he is not pictured wearing his blazer, he will most likely be in a Doug Hayward gabardine suit - single-breasted 9oz tropical weight. He is rarely seen without his brown briefcase, containing a spare pressed shirt. He doesn't like to be photographed in an armchair ("It's not my style") and he won't do advertisements for unsuitable products, such as beer or chicken soup ("It doesn't fit"). At one stage of his career, Whicker was regarded by the Independent Broadcasting Authority as such an important figure that he was banned from doing any advertising at all.

When he finally signed with Barclaycard in 1984, the deal lasted for six years and offered yet more exotic locations, as he was filmed having his credit card snatched by a performing dolphin in Florida and sending up a popular Cornetto ice-cream commercial as he glided in a Venetian gondola.

The latest campaign was filmed over four days last week in Cape Town, where the varied local terrain was used to depict the continents of the world. Koelbaai beach became Australia, and the Stellenbosch vineyards served as France. The pine forests around the Grabouw Country Club passed as Canada.

Such trickery may be accepted in advertising, but Whicker is scathing about the growth of fakery in factual television, accusing those responsible of "conning their way into the ratings and devaluing our currency". In his last book, Whicker's World: Take 2, he said: "In more than 40 years of filming documentaries for the BBC and ITV, neither I nor my directors and producers ever for one second considered faking a single significant shot."

The television presenters he admires are his friends Michael Parkinson ("I don't know how a chat show could be better done") and David Attenborough. Asked for a younger name, he cites the BBC correspondent Rageh Omaar. He condemns modern "mandatory blonde" travel presenters for not being able to "tell their Aran from their Elba".

The BBC's failed attempt to replace Whicker with the jazz pianist Jools Holland obviously hurt him. But Michael Palin, the Python who - despite the Whicker Island sketch - followed him into adventurous travel journalism, is acknowledged as having a "nice persona". Louis Theroux, who was reportedly inspired by Whicker, is not quite so well thought of. "It's a different ball game, isn't it? A slightly different attitude. He wanted to do me. Of course I turned him down; it would have been ridiculous. It's not my scene."

Whicker could be forgiven for being a little cautious after a hatchet job by the Daily Mail, which marked his 40th anniversary in television with an interview-based piece suggesting that he was a stumbling old man past his sell-by date. It was a bad call; research for his latest advertising project suggested that Whicker has an extraordinary following among the travelling generation of twenty and thirty-somethings who see him as a pioneering adventurer and a voice of authority, the man who got to their favourite destinations first.

He may be pushing 80, but he has no intention of resting and will start on his next book as soon as he gets back from South Africa to St Helier in Jersey, where he lives with his partner Valerie Kleeman (who assists him on all his trips, taking photographs and bringing him tea as he emerges from holes in the beach).

But he probably won't be in Jersey long. "I get itchy feet, I'm afraid. You want to be up and moving," he says. "It's one's life. I have been writing all my life and talking to camera since 1957. It's the way you think."

Mr Fahrenheit won't be stopping just yet. He's still having a ball.