Line of attack: Gerald Scarfe at 70

"Lavatory wall artistry" was the succinct verdict of Monmouthshire councillor Clive W Venn as he triumphantly brought to a climax his campaign to force an art gallery to remove from public view a series of Gerald Scarfe cartoons that had offended his decency.

Councillor Venn, chairman of Newport Corporation's amenity and leisure services committee, was so offended by images that included a drawing of Harold Wilson au naturel and surrounded by the Gnomes of Zurich, also naked, that he persuaded Newport Art Gallery to take them down.

You could say Scarfe's career has survived this setback, which took place 35 years ago this month. This "lavatory wall artist" is now as much of an institution as you will find anywhere in the British press. He will, without fanfare, celebrate his 70th birthday on 1 June, and on Saturday morning will faithfully submit for publication his weekly political cartoon for The Sunday Times, for whom he has worked since 1967.

Throughout an extraordinary career that has seen him compared to the 18th-century caricaturist James Gillray, Scarfe has provoked controversy and persistently prodded the boundaries of what is deemed acceptable. "I have been up against censorship all my life," he says. He risked offending his ultimate employer Rupert Murdoch, just after the media tycoon's takeover of Times Newspapers, by drawing an unflattering cartoon of Ronald Reagan. "Poor old Ronnie," Murdoch is said to have commented within the earshot of journalists who feared the worst for Scarfe.

A later drawing, of Diana Princess of Wales being raped by the press ("of which I am a part"), has yet to appear in a newspaper. "It has been exhibited and been shown on the BBC," says a somewhat mystified Scarfe. "It was on a programme on portraits the other day and they showed it before the watershed."

More recently he fell foul of Chinese printers, who objected to a drawing he had made of Chairman Mao ("he's dead but still holds fear over the people") alongside some "extremely large willies". "They said, 'Too big!'" recounts the cartoonist wryly, adopting a Chinese accent. "So I said, 'That's the way we are in Britain.'"

Genitalia, ugly naked bodies, faeces. These are as much the signature ingredients of Scarfe's work as the familiar cross-hatched style in black Higgins ink, scratched on to a sheet of Green & Stone of Chelsea paper before being translated to newsprint.

It has been this way since he first came to prominence after joining the then fledgling satirical magazine Private Eye in 1961, where he was encouraged to do risqué caricatures by the likes of Willie Rushton, Peter Cook and Richard Ingrams. "I found I could draw pubic hair and warts and pimples and shit if I wanted to. It was just pushing the limits at that time. That's when I came to notoriety." Scarfe talks with an easy vulgarity which is at odds with his elegant appearance (crisp white cufflinked shirt, brown jacket, new suede boots) and the boutique Chelsea hotel where he has asked to do the interview.

"Sex is very funny, I find. It's a great vehicle for showing the vulnerability of us all. People say 'Why do you draw so many naked bodies?' and I say 'That's us at our most vulnerable'. We are all stumbling around this planet, not knowing what to do. It seems I can express myself at that level."

In recent months, Scarfe's efforts have been recognised by his peers as never before. Last November he was ranked, by a distinguished panel that included his former editor at The Sunday Times, Sir Harold Evans, as one of the 40 most important newspaper journalists of the modern era. In March he was recently named Cartoonist of the Year in the British Press Awards.

But this was the first industry prize Scarfe has won in 40 years. Despite his significant public profile and his accommodating manner, he is not universally admired by colleagues. In a profile in the now defunct Sunday Correspondent in 1989, the cartoonist Martin Rowson (The Guardian, Daily Mirror, The Independent on Sunday) raged at the apparent contradiction of Scarfe's "horrid" drawings and the "irredeemable tweeness" of his home life with the actress and famed baker of cakes Jane Asher. Scarfe, Rowson suggested, was not a great artist but an unfunny caricaturist with an unoriginal style. "Like all second-league artists who are never quite going to make the grade - rock musicians, journalists and most of all cartoonists - he labours under an exaggerated sense of his own importance."

Last October, The Daily Telegraph's Nicholas Garland expressed boredom at Scarfe's "remorselessly simplistic approach" and compared the "screaming pitch" tone of The Sunday Times cartoonist to the piano playing of his baby grandson. ("That's very clever, darling. Look here's your tractor.")

Scarfe, who says he "wouldn't slag off a fellow artist", claims not to be previously aware of Garland's criticisms but seems unperturbed by them. The charge, he says, is certainly not true of his "gentle" artwork for the English National Ballet's The Nutcracker. "But if he's talking about my political work alone, that may be true. I've always been accused of taking a sledgehammer to crack a nut, of overdoing things. But I think sometimes my cartoons aren't hard enough."

To illustrate this last point he cites an encounter with Tony Blair, during which the cartoonist mentioned that he was sometimes accused of cruelty. The Prime Minister said he didn't find Scarfe's drawings cruel. "I said, 'I must try harder in future.'"

Scarfe begins his day at 5.30am and shortly afterwards is scouring the six national newspapers he subscribes to (the four qualities plus The Sun and Daily Mail), looking for inspiration. "Quite often I tear the photographs out. You might see Blair with a certain facial expression you might use."

Having read the papers, he stands up in front of his desk, which looks out over the Thames, and with his "very, very hard steel-nibbed pen", he starts work. "I work from the shoulder and I sort of lash it on the paper. There's a huge force on the nib," he says, sweeping his arm violently out to the side, left to right. "Ideas are like dreams: if you don't get them down they evaporate. I like to get the bare bones down. That's the idea. Sometimes it doesn't go right the first time. I can sometimes tell within six lines of the pen that it's not going to work the way I wanted it to. I chuck the paper behind me and go on to the next. Sometimes I've got 20 or 30 sheets behind me."

If a drawing doesn't work out, Scarfe says he doesn't mind, for this is a cathartic experience. "I have to do it. It's not something I just do for a job. I love drawing and I have to unload these ideas. I have to complete them and hopefully, if there's a book, they will appear."

Speaking to The Daily Telegraph in 1970, Scarfe had said: "People think of me as an artist but primarily I'm a diarist, a journalist." Nowadays, he seems to be happier to embrace a loftier status. "I'm an impetuous artist and that's probably why I'm a journalistic artist."

His art is compromised by deadlines and he readily admits to sometimes submitting what he describes as "potboilers", when he's not been able to think up something more original. "It's something when I know I have not produced the best I can but I have to produce something in the deadline time. Later in the evening I think, 'Bloody hell. I could have done that.'"

Some of the recycling is easily justified. Scarfe has reworked his all-time favourite cartoon, which showed a starving child marked "A" and some food marked "B" alongside a caption condemning world leaders for failing to solve the apparently simple problem of joining "A" to "B". The drawing - conceived for the Biafran war of 1972 - has, to Scarfe's dismay, not lost its relevance.

Not that he thinks of himself as an agent of change. "I bashed Nixon for years and drew him as the creep he was. But something from an artist's imagination is just that. It was Woodward and Bernstein who brought Nixon down."

People see cartoonists as mavericks or jesters. "They would say that, wouldn't they, because they're eccentrics," he responds.

He doesn't deny the global impact of the Danish cartoons of Prophet Mohamed but suggests they are "the exception that proves the rule". As for subject matter of the cartoons themselves: "It's patently stupid. It's saying all people who belong to Islam are suicide bombers, which as we know is nonsense."

Gerald Scarfe had a middle-class childhood in London but one in which he was largely confined to bed, racked by severe breathing difficulties that left him pigeon-chested and hunchbacked. In his entry in Who's Who he records his education as "scattered (due to chronic asthma as a child)". When he was eight years old, he was lying in bed on a hospital ward in the middle of the night when an adult patient shuffled to the window, gasping for breath before dropping dead. Scarfe's sickly childhood gave him time to develop his talent for drawing and shaped the imagination that would define his later work.

When he left school at 16, little was expected of him. "My parents didn't think I could make a living because I was such a chronic asthmatic."

Having failed his interviews to gain employment in banking, he entered a commercial art studio, where he developed his skills as a draughtsman but was unfulfilled, depicting cutlery and crockery. "I felt I was prostituting my art. I was drawing this crap. It was before the days of photography and I had to take these terrible goods and make them more glossy and enticing."

Punch offered him his first taste of seeing his work published. "They paid me seven guineas and if I sold 10 a week I was making a huge amount of money."

But Scarfe, who was increasingly fascinated by anatomy, hankered after recognition that he was a serious artist and interrupted his cartoonist career by getting a place at the Royal College of Art. "I went for two weeks. It became clear to me that it was too late and all I really wanted was to be attached to the RCA. I was earning a lot of money outside and I couldn't bear the thought of going back to school. I have often thought that if I'd stayed I would be a painter now, working in the style that I do and working in the theatre, as I do." Scarfe's son Alexander is studying to be a painter. "He's following in his father's footsteps but as a real artist."

When Scarfe's provocative work for Private Eye brought him to the attention of Fleet Street, he was courted by the Mail and the Express. The Mail's owner, Vere Harmsworth, and its editor Mike Randall took him out to lunch at Caprice. When Randall said Scarfe could have £5,000 a year and a company Rover, Harmsworth upped the ante: "Let him have a short life and a merry one. Give him an E-type and six." Scarfe says that wasn't his primary concern. "I already had a car. What I was trying to find out was whether they'd let me do what I did at Private Eye."

Nevertheless he took the job, whizzing round swinging London in his Jag, not wearing a seat-belt. But it didn't last. "People at the Mail said to me, 'We can't print your drawings.' The paper is such a familiar thing that comes through the letter box every day and the effect would be the same as if the family dog had shat on the table."

Harold Evans took Scarfe to The Sunday Times in 1967 and there he has remained. At first Evans wasn't sure of how to deploy him.

Scarfe was sent to Northern Ireland to do reportage on the early days of the Troubles. Heading to Derry's violence-torn Bogside he parked his car next to a barricade and settled down in the passenger seat "with my sketching materials" to draw the scene. After a knock on the window, Scarfe was advised by some young men that they "might need your car" but protested that his hired Ford Cortina "wasn't insured".

"Then about three minutes later this Ford Zephyr pulled across the front of the car. Without a word these men got in and said 'This is official' and started driving."

Scarfe was taken to a housing estate but to his surprise the terrorists set him free, even retrieving his coat from the boot before allowing him to depart. "I just walked away with that particular feeling in my neck. I heard afterwards they liked Cortinas because they had big boots. They blew up the Post Office the next day and I left."

After a spell drawing theatrical subjects from Laurence Olivier to Cliff Richard, Scarfe's aptitude for caricature drew him towards politics. He has become a fixture of The Sunday Times' leader page, where he is still published in black and white, though he uses colour in his drawings.

Still famed for his drawings for the cover of the Pink Floyd album The Wall, he has also produced T-shirts for the Rolling Stones. "I work in the theatre and rock and roll," he says, matter-of-factly. He has won awards for his costume design and as an autobiographical film-maker, though his Bafta for the latter "has gone dark brown and the plaque with my name on has fallen off".

Approaching 70, Scarfe is energised by events in Iraq. "The Iraq war has been a great trigger for not only me but a great many cartoonists," he says. "The premise on why we went to war and the mess now. Bad news is good copy and the villains produce the best cartoons."

Causing a stir is no longer so easy when the censorship of the days of Councillor Venn is no longer around. "We are all now used to Spitting Image and people can say bugger, bum, or arsehole - even fuck in the right context. It's quite a different climate now."

The response of this great draughtsman has been to make his work - which he says is competing for attention with headlines and advertisements - less and less elaborate. "When I first started, I used to draw every single pimple, every nasal hair, every pore almost of the body," he says. "I now go for an overall shape and something fairly simple. The simpler my message, the more it whacks you in the face."

Long may Scarfe's power remain undiminished.