William Turnbull: Too good to be forgotten

There is a large stone sculpture in the foreground of David Hockney's famous painting American Collectors which stands almost as tall as the two figures – Fred and Marcia Weisman – who flank it on either side. And if you look at Hockney's other Los Angeles-era painting Beverly Hills Housewife you will spot a long, totemic sculpture amongst the expensive furnishings on the canvas.

The Hockney paintings – large, spacious, epitomising a cool Californian artistic zeitgeist – will be familiar to many. The objets d'art that Hockney incorporated in his work will not be nearly as recognisable. The artworks featured by Hockney were created by William Turnbull, an artist who was avidly collected by the American super-rich in the 1960s and 70s, was represented by the prestigious Marlborough Gallery in New York alongside Willem De Kooning, Jackson Pollock and Mark Rothko and is considered by art cognoscenti to be on a par with Giacometti.

Yet, at the age of 89, Turnbull is the greatest unsung – or forgotten – hero of the British sculptural scene, as far as popular acclaim goes. While he is revered by gallery directors, collectors and international artists, he has never gained the recognition that many think he deserves.

Now, his son, Alex Turnbull, has produced and co-directed a film describing his father's life and accomplishments. In it, the art world has banded together to celebrate his sculpture and painting – two mediums which he mastered equally. Some of the most prominent characters in the British art world discuss his work's groundbreaking importance, and the conundrum of why he has never been as appreciated in Britain as abroad.

Sir Nicholas Serota, director of Tate Galleries, Antony Gormley, the late Richard Hamilton and Peter Blake all give high praise in the film, Beyond Time. Jude Law – another admirer who calls his work "potent, powerful and simple" – narrates the film, which will premiere at London's Institute of Contemporary Arts (ICA) on Thursday, in association with Vanity Fair magazine, in front of a hip new generation of fans including Kate Moss, Goldie and Ian Brown.

Turnbull, a contemporary of Giacometti who became friends with the Italian artist while living in Paris, and who dined with Rothko while living in New York, has a career spanning 70 years. He was born in Dundee, and after serving in the RAF, arrived at the Slade School of Fine Art. After a time, he became disenchanted with painting and transferred to the sculpture department. In his voiceover, Law says that Turnbull became suspicious of "beautiful materials" and began working with plaster. "With this one bag of dust," he adds, "he was making something out of nothing."

After Slade, Turnbull found himself at the vanguard of a subversive movement known as The Independent Group, who created waves between 1952 and 55, positioning themselves in direct opposition to an art establishment they saw as pompous and over-formal. The firebrand group were one of the four main artistic movements in post-war Britain, alongside R B Kitaj's School of London in the 1960s, a mid-70s wave of creativity and the YBA movement of the 90s. "The Independent Group was as important as the YBAs in that time. They were seen as a major new voice in European art," says Serota.

Turnbull was also chosen to showcase his works at the Venice Biennale in 1952. Tim Marlow, an art historian, talks of this moment as a turning point for British sculpture. Turnbull was shown alongside his fellow sculptors Reg Butler, Kenneth Armitage and Lynn Chadwick, whose work was praised for summing up postwar angst with its "geometry of fear". "They put young British sculptors on the map," says Marlow. Gormley also reflects on Turnbull's uncanny ability to "make you think that a small thing has endless space."

In a sense, it was Turnbull's flair for painting as well as sculpture that became his most problematic feature; it confused the British art establishment. Serota notes that "people are always suspicious of polymaths, of people who work in more than one medium."

Others argue that this is a particularly British form of classification – Giacometti, Matisse and Picasso were recognised for their achievements in both sculpture and paint, not stigmatised for them. The American art world loved Turnbull's ambidextrousness even as Britain turned up its nose, and he became a far bigger figure across the Atlantic.

Turnbull, for his part, was drawn to the New York arts scene, says Marlow, and was "opposed to the parochialism of the British art scene." He turned away from figurative art, and towards abstractionism, which Britain never really welcomed in the way that America did. Turnbull's work became big business in New York and LA, snapped up by collectors such as Ted Power, Betty Freeman (who featured in Hockney's Beverly Hills Housewife) and fans of Rothko's paintings.

Despite a number of major retrospectives – Tate in 1973, Serpentine Gallery in 1995, the Tate's Duveen Galleries in 2006 – Turnbull remains an artists' artist to some degree, highly respected by his contemporaries.

Alex Turnbull says he decided to make a film about his father's life five years ago. "I began finding out just how much he had done. I found a letter sent to Bill by Rothko thanking him for coming to the house..."

He thinks that popular acclaim may have eluded his father because he refused to take part in the crafty power play which fuels the art world. "He was headstrong. He told so many people where to go. In terms of art politicking, he smashed through it, he just didn't care. Bill was the original punk, a rebel with a cause."

'Beyond Time' screens at the ICA, London SW1 (020 7930 3647) 25 November to 1 December