AS HIS biographer, Sir John Richardson's life has been marked by Pablo Picasso. When I meet the newly knighted 88-year-old at the Ritz shortly before the opening of Tate Britain's new Picasso exhibition, his principal regret is that he didn't allow his actual body to be marked by "the greatest artist of the 20th century".
"Picasso was very cross when I came back from America and I had a new tattoo here," Richardson gestures to his right arm where a faded mark is visible. "He said: 'I would have tattooed you!'" Richardson is dressed soberly but the fluorescent Paul Smith socks suggest a flamboyant spirit. He speaks with animation and precision remarkable for a man of his age. His eyes, he tells me, are "gone", requiring monthly injections, and his short-term memory is fading. However, when he recalls the days when he lived in the South of France with his lover, the collector and scholar Douglas Cooper, and Picasso and Jean Cocteau were regular house guests, his memories animate figures who, for most of us, remain abstractions, superlatives.
Apparently Picasso had always hoped to do a Cubist still life on someone's back. He was about to do one on Georges Braque in Paris, in fact, but the First World War intervened. It was perhaps Picasso's preference for the DIY "prison" method (needle, ink, pain) that put Richardson off -- "It would have hurt."
Richardson was born in London in 1924 and now resides in New York, where his Fifth Avenue apartment resembles an Italian palazzo and contains one of the largest penises in the world, purchased from a whaling museum. Richardson has recently been employed by the New York dealer Larry Gagosian and has been working on a series of late- Picasso exhibitions. However, this London visit allows him to catch up with old friends.
He is due to have a private tour of David Hockney's landscapes show at the Royal Academy after we meet. Then he will attend a dinner for the friends and family of Lucian Freud. He sat for both. The Freud portrait is in the National Portrait Gallery's current exhibition -- Freud would recite Rudyard Kipling poems and Cole Porter lyrics as he painted, a process Richardson describes as "absolute heaven".
Richardson also sat for Andy Warhol, was a friend of Francis Bacon, toured Venice with Truman Capote and ushered at Sir Cecil Beaton's memorial service in New York. He has been Greta Garbo's landlord and Salvador Dali's dealer. He emits a pained noise when I ask what he thinks of Damien Hirst, before deciding: sharks good; paintings disaster.
However, it is his love for Picasso that is his grand passion. A Life of Picasso, which he began in 1991 and now runs to three volumes, is a definitive work, combining scrupulous scholarship with personal anecdote. "The more I work on Picasso, the more convinced I am that he was the greatest artist of the 20th century," he says. "This thing he had of turning dross into magic. He was a virtuoso draughtsman. No other 20thcentury painter could touch him."
THE task (Picasso died aged 92 in 1973) is overwhelming. "The difficult thing with Picasso is that whatever you say about him, the opposite is also true. You can say he was monster and a shit but he was also an angel of generosity and kindness." The most angelic thing he ever did for Richardson was to identify methodically the inspiration for his portraits. "He went through them and said, you see, 'Many of these pictures are of my mistress Dora Maar or Marie- Therese [Walter] but these ones, there are as many as four different identities in the one portrait.'" Often, Picasso would paint a blonde model, dreaming of a brunette. And all his guitars were mistresses.
It is principally for this huge work that Richardson was recognised in the Queen's Honours list. For his investiture he was offered Prince Charles -- "but I wanted to be knighted by the Queen, and she's only …