David Hockney: Northern lights

Many artists are famous, but only a handful achieve the level of movie-star celebrity: Picasso, Dali, Warhol, Damien Hirst. Hockney is one of them and had come to the conference to do battle with Labour's plans, outlined last November in a White Paper, to ban all smoking in licensed premises. He defended the right of smokers to pursue their pastime and objected to the puritanical bossiness of this government.

A man of strong libertarian instincts - he opposes the fox-hunting ban on similar grounds - he took the stage at a packed meeting organised by Forest, the pro-smoking lobby group funded by the tobacco companies, and declared: "Death awaits you whether you smoke or not. Picasso smoked until he was 92 and Matisse until he was 85."

Hockney, not a heavy smoker himself, is now 68. He thinks of smoking as a species of self-medication: "I smoke for my mental health. So do most people. If I wasn't smoking I'd be on anti-depressants. I prefer cigarettes."

His arguments in defence of pleasure were stronger than some of the others he offered. The assertion, for example, that bohemia would cease to exist if artists were forbidden to smoke in pubs seemed less about contemporary Britain than a harking back to the country he left in 1964 for the sunshine and freedoms, both social and sexual, of California. He is very conscious of the irony that much of the land of the free has now succumbed to anti-smoking bans: "I don't like going to New York much any more. It's a smoker's nightmare."

Over the past year, his defence of smoking has become a passion, almost an obsession, but Hockney has a tendency to acquire bees in his bonnet. His last one was inspired by a visit to the Ingres exhibition at London's National Gallery in 1999. He became fascinated by the many pencil portraits Ingres had made in Rome around 1810. They were small, smaller than a sheet of A4, but uncannily lifelike and "accurate". What was even more astounding was that they were all done rapidly, most in the course of a day, and all the sitters were strangers to the artist, wealthy visitors to Rome eager for a souvenir.

Hockney is, of course, a celebrated portraitist: his Mr & Mrs Clark and Percy is the most popular picture in Tate Britain and the only work by a living artist to feature on the shortlist of the recent BBC poll to find the most popular painting in a British gallery. He knows how hard it is to catch a likeness, even of someone one knows well, and was eager to find out how Ingres had done it. His researches led him to experiment with a camera lucida, an optical device which "projects" images on to paper, and he soon persuaded himself that he had discovered Ingres' method.

Even more, he became increasingly convinced over the next two years that he had stumbled on a secret history of Western art. His investigations with the camera lucida, the camera obscura, various mirrors and lenses led him to suggest that as early as van Eyck's The Arnolfini Marriage in 1434 artists were using optical devices to create their paintings and that this had major consequences for the representation of the physical world: the dramatic light and shade, for example, of much of Caravaggio's work. In 2002, Hockney published his ideas in the copiously illustrated Secret Knowledge: Rediscovering the Lost Techniques of the Old Masters which caused considerable controversy.

Though Hockney had chased various optical hares through 600 years of art history, he was unable to prove a single example of an artist using mirrors or lenses, not even Vermeer and Canaletto, the two cases with the most circumstantial evidence. Most art historians and critics were not convinced. The critic Brian Sewell gave it a damning review and later observed that "not since the Nazi art historians laid claim to the Renaissance has there been a more mendacious, misleading and meretricious book".

Sewell also suggested that Hockney had a personal motive for arguing that Leonardo, Caravaggio, Constable and Ingres used the high technology of their day to produce their masterpieces. Ever since the late Seventies, Hockney had been serially fascinated by various gadgets - the Polaroid camera, the Quantel lightbox, the photocopier, the fax - and had used them in the creation of his art.

He began to question classical perspective and starting seeking ways to represent movement in space. Although this period did produce some interesting works, like his Polaroid montages - colourful cubist desert landscapes and deconstructed figures - the critical response was generally disappointing. Sewell concluded he had been seeking the authority of the Old Masters for these unsuccessful experiments with technology.

It's a pregnant speculation. The current critical consensus on Hockney is that his important work was produced between 1959, when he first entered the Royal College of Art in London, and the middle of the 1970s. This view is supported by the prices his works now fetch at auction. Earlier this year a painting from the 1960s, Seated Women Being Served Tea, fetched £1.8m at Sotheby's, the highest sum ever paid for a Hockney, but recent pieces at auction tend to go for tens of thousands rather than hundreds.

It's certainly true that Hockney and the Sixties were made for each other; it was a period when being a working-class northerner had ineffable chic. He was born in Bradford in 1937. The strong-mindedness, occasionally shading into obsession, with which he pursues his hobby horses, whether smoking or lenses, was apparent in his parents: his mother Laura was religious and a vegetarian; his father Kenneth an anti-war campaigner who fiercely opposed smoking. They were the subject of one of his finest double portraits in 1977.

Hockney attended Bradford Grammar School, and at the age of 11 decided that he wanted to be an artist. After a course of traditional study - anatomy, perspective and life drawing - at Bradford School of Art, he refused to do his National Service and worked for two years in local hospitals. He arrived at the Royal College of Art in London in 1959 where his fellow students - a notably brilliant year - included R B Kitaj, Allen Jones, Peter Phillips, Derek Boshier and Patrick Caulfield, who died on Thursday.

His habitual candour about his homosexuality - years before it ceased to be a criminal offence - and his passion began to create poignant confessional works such as We Two Boys Together Clinging (a line from Walt Whitman). By the time he won the RCA's gold medal for work of outstanding distinction in 1963, his final year, he was already famous for his camp wit delivered in his flat northern accent. He accepted the medal from the Queen Mother in a gold lamé jacket and gilded shoes - which was a considerable male fashion statement for the time. He also dyed his hair blond for the occasion and kept it that way.

Paul Kasmin became his art dealer and his work sold as fast as it could be produced. Hockney was among the two dozen or so figures who epitomised the Swinging London of the period and whom the press dubbed the New Aristocracy or the New Class: David Bailey, Terence Donovan, the Beatles, Mick Jagger, Jean Shrimpton, Mary Quant.

In 1964, he moved to Los Angeles, a paradise after the constraints of a still stuffy England, and within a few years had constructed in his work the still iconic version of the city: blue sky, brown bodies, blank glass panes, writhing reflections in swimming pools. Though based in LA, Hockney often returned to London - and to his parents in Bradford.

Throughout his career, he has worked with great success in other media than painting: exuberant set designs for operas such as The Rake's Progress at Glyndebourne and wonderful book illustration for Grimm's Fairy Tales and the poems of Cavafy.

The Seventies brought some of his finest painted portraits: Mr & Mrs Clark and Percy, Christopher Isherwood & Don Bachardy and several pure line ink life-drawings - the portrait of W H Auden and many pictures of his boyfriend Peter lying around in hotel rooms.

Tom Lubbock, The Independent's art critic, finds these drawings astonishing: "Here every stroke is on its pins, ink forbidding error. No corrective back-tracking. No anticipatory roughing-out. The drawing is like that toy where you have to manoeuvre a ring very carefully around and along a serpentine wire without touching (if you do a bell goes off); it is fatal to rush, equally fatal to hesitate, until the end. These drawings are watchable from moment to moment, as the lines track their way round each representational problem without losing sight of the whole emerging picture. If there is a case for drawing, drawings like these must be the leading exhibits."

Hockney's work is suffused with sensuous pleasure; especially compared to Lucian Freud, the other contender for the title of greatest living British painter, there is little apparent of the dark side of human existence. But though there was calm in the later LA pictures and landscapes, there was also an increasing melancholy. The artist began to go deaf in 1980 and admits that he leads a quiet, rather solitary life nowadays.

As he has grown older, the more exotic elements of his character have receded and the more traditional English virtues, which were always there, have become more apparent: lack of arrogance, modesty, hard work, common sense. Andrew Marr interviewed him last year in LA. In the corner of his studio, there were placards reading "End Bossiness Soon". "Soon?" Marr asked. Well, Hockney explained, "'End Bossiness Now' seemed a bit peremptory, you know, not very English."

A Life in Brief

BORN 9 July 1937, in Bradford.

FAMILY Parents: Kenneth and Laura Hockney.

EDUCATION Bradford Grammar School; Bradford School of Art; Royal College of Art, London.

CAREER Graduated from the Royal College of Art in 1963 with the gold medal for work of outstanding distinction and immediately became the most famous artist in Swinging London. As well as paintings, he has done important work in stage design for opera, illustration and etching. In 1964 he moved to Los Angeles where he still lives. He is a member of the Royal Academy and was made a Companion of Honour in 1997.

HE SAYS "The moment you cheat for the sake of beauty, you know you are an artist."

THEY SAY "Between 1960 and 1962 David Hockney created some of the most sensuous, exuberant and unbuttoned painting seen in Britain since the Second World War. The young Hockney brought a coarseness, a vigour and a passion to all he touched."

Andrew Graham-Dixon, art critic