Royal family's favourite portrait painter reveals secrets of the royal sittings So, how did he go about painting the most recognisable face in the world? "I wanted to convey her extraordinary inner-strength and steadfastness," he says of the Queen, whose portrait he painted between 1989 and 1991. She was always punctual for sittings in the Yellow Drawing Room at the Palace, save for one occasion, where she appeared slightly late, with her jewelled diadem slung around her arm. "I think I must have looked quite surprised to see it hanging from her arm," says Stone. She made her apologies and said it was very difficult to run with it on her head. I think she'd also taken off her shoes to get a better grip on the carpet as she rushed for the sitting. The Queen declared the painting would "make a good stamp" and confided that she was not always so thrilled with other portraits. "One would with to consign some of them to the basement," she told him. Aged four, Stone stood at the gates of Buckingham Palace on his first trip to London and announced to his parents: "I'm going to paint the Queen." It seemed an unlikely prospect. The son of an Essex postman, he grew up in a "two-up, two-down" near Colchester, devoid of artistic influence where the only royal image was a photograph of the young Queen on a biscuit tin. Now, the hallway of his detached house in the same area leaves no question mark over his success. Lithographs of his paintings of the Queen and Queen Elizabeth line the walls, together with recent studies of the Duke. In his studio, preparatory sketches and oils of the Prince of Wales and the Duchess of Cornwall are propped against bookshelves, heaving with photographs of meetings with other prominent sitters, including Nelson Mandela and Baroness Thatcher. Since his first royal commission, Stone, 61, has become the most prolific royal artist of his day, painting members of the Royal family spanning four generations every year since. A near-fatal accident shortly after that first childhood glimpse of Buckingham Palace unexpectedly propelled him towards his goal. Stone fell down the stairs of his family home, fracturing his skull. In a coma for weeks, his parents were told to expect brain damage. "When I finally came round, I was completely deaf," says Stone, who eventually regained the hearing in his left ear only. They couldn't do much with me at school so the teachers gave me paper and paints. I was at my happiest painting - it was my escape. Visiting the Royal Academy's summer exhibition in 1965 aged 14, sealed the deal, when he was mesmerised by the paintings of Sir Gerald Kelly, the Academy's former president whose state portraits of George VI and Queen Elizabeth were widely acclaimed. "His portraits stepped out of the frame to shake me by the hand," Stone recalls. I wrote him a fan letter saying I thought he was the greatest thing since Rembrandt, I too wanted to become a portrait painter, and could he give me a few tips? Sir Gerald became Stone's mentor and tutor, often recalling how Queen Elizabeth was his favourite sitter. Despite rejections by several art schools including the Royal Academy and the Slade, in 1973, Stone, then 22, decided to try his luck, and telephoned Clarence House, where he was put through to Lord Adam Gordon, Queen Elizabeth's Comptroller. The conversation went thus: ""Mr Stone, Queen Elizabeth is very busy and couldn't possibly sit for any Tom, Dick or Harry who should call." I said, "Lord Adam, with great respect, don't ring off, I could be a latter-day Rembrandt."" Stone reddens remembering his lack of modesty, which paid off. Soon after impressing the Comptroller with examples of his work, he received his first commission to paint Queen Elizabeth for the Royal Anglian regiment, of which she was colonel-in-chief. The pair developed a strong rapport, with Stone painting her six times, including the year before she died. He proudly tells me he was invited to stay for lunch after only her third sitting - most other artists were usually asked to lunch only after the final sitting, if at all. "The sittings were hugely entertaining - as were the lunches," he says. She'd always make you laugh and was a great storyteller because she knew how to time the punchline. Every moment was to be treasured because she was a very special lady. During their sittings in the Garden Room at Clarence House, she would often wander round to Stone's side of the canvas to view progress, and was usually pleased with the results. "Once, she put a finger up to the canvas, and asked me: "Do you mind taking a little off my waistline?" I said "I'll keep painting away and you tell me when to stop." Well, it became the reintroduction of the wasp waist. After she left, Stone poured himself a stiff gin and tonic and returned her waist to its original girth. "She would take me all over Clarence House to see pictures that meant something to her," he adds. What is quite special now is that the Prince of Wales will on occasions ask me to talk about certain pictures that he has, that were owned by his grandmother, and for me to share with him the story behind the picture that the Queen Mother had told me. It's a huge privilege to pass it on to him. Stone has painted the Prince twice. We talk a lot about his grandmother - they adored each other - and about his painting, though he's far too modest to show me his work. As a companion to spend time with he's absolutely fascinating, because of his breadth of interest, passion and humour. He's also a very private person - but it's not my job to probe, my sittings are not interviews. The Duchess of Cornwall has also sat for him twice. "She's really nice," he says discreetly. We talk about family and things. Stone lives with his second wife Rhonda, and their son, William, 18. He has two daughters, Flavia and Chloe, from his first marriage. "It's always friendly, but I'm not their friend," he says pointedly of the royal sittings. A recent postcard from the Duchess written while on holiday in Scotland is propped against the dining room mantelpiece, thanking him for sending a sketch, affectionately signed "Camilla." The Duke of Cambridge and Prince Harry were also recent subjects for what he will only describe as "a private commission." "They are very nice young men," he says. Princess Margaret was an altogether trickier subject, often failing to show, without notice, for sittings at Kensington Palace during Stone's commission in 1981. Then divorced from Lord Snowdon, the Princess was involved with Roddy Llewellyn. "I was kept on my toes - the sittings could be hugely entertaining but also anxiety-ridden," he says. If she didn't feel up to it, she didn't hide it. But she was a great raconteur, razor sharp and a wonderful mimic. I was the subject of her savagely critical wit. She once looked at one of my studies and said "As you know, I have been suffering from flu for the past week. It appears that you have caught it."" During the sittings, Princess Margaret went on holiday with Llewellyn, and returned, Stone thought, looking tanned and radiant. I asked her if she had a nice holiday and she replied that it was the worst holiday ever. I didn't probe and assumed the weather must have been dreadful. Stone later learned that during the holiday, Llewellyn told her that he planned to marry somebody else, but his portrait of her depicts a serene Princess, masking her private turmoil. Although the Queen was delighted with her portrait by Stone, the public response was mixed, with some sections of the press surprised that he had dared paint the Queen with lines on her face. One headline read "Royal Wrinkly Rumpus." So he is familiar with the furore that recently greeted Paul Emsley, the artist who painted the first official portrait of the Duchess of Cambridge, which was savaged by the critics when unveiled at the National Portrait Gallery in London last month. "I didn't think it was as bad as everyone said it was," he says diplomatically. It's very difficult painting a beautiful, very famous young lady. I would like to paint her, but I don't know whether after the reception that first portrait got she's in any mood to sit again. Baroness Thatcher has sat for Stone six times. One portrait, commissioned by Gordon Brown to mark her achievements, hangs in her former study at Downing Street - the only original painting of a prime minister to grace Number 10"s walls. "Actually you're sitting in her chair," he says of my seat at his dining table. She's been here many times. Once, she was describing an incident in the Falklands, and started demonstrating what was happening with battleships and battlelines by moving the tea set around. Does he ever wonder how he has pulled off becoming most successful - and trusted - artist for capturing the public and private face of the monarchy? I don't spill paint on the carpets and I don't gossip. Richard Stone supports the Nyumbani Children's Home in Nairobi, Kenya. Art created by the children at Nyumbani is being auctioned at www.nyumbani.org.uk until March 7