Prince Charles' first public appearance with his long-time mistress Camilla Parker Bowles has signalled a new phase in their search for public blessing for their relationship. The heir to the British throne left a private function on Thursday with Parker Bowles to a blaze of flashing lights from more than 100 photographers and television crews who had been waiting years for such a moment.Tipped off to expect the couple's first joint public appearance, they had been staking their places on the pavement outside the Ritz Hotel since the day before. Charles and Parker Bowles' appearance - after years of avoiding paparazzi lenses - signalled the couple now view their relationship as `official,' press commentators said.Parker Bowles, 51, arrived for her sister Annabel Elliott's birthday party earlier than Charles, 50, along with her son Tom, 23, and daughter Laura, 20, but the couple Left together. As they walked down the steps, Charles put a hand on her back to steer her to a waiting car, a sign offamiliarity the press pack had prayed for.Their pictures dominated Friday's press, taking up whole front pages, with acres of newsprint devoted inside to the story. Charles and Parker Bowles have taken great pains never to be seen together in public, despite a relationship stretching back to before he married Diana, Princess of Wales.The couple have been at the same functions, such as a society wedding late last year, but always arrived and left separately and discreetly. Their relationship began in the 1970s, but was put on hold when they both married. Neither marriage survived.After their respective divorces they attempted gradually to secure greater public acceptance, but that was again put on hold following Diana's death in Paris on August 31, 1997.Since Diana's death, she and Charles had not appeared in public together, although they had been seen separately at occasions such as their respective 50th birthday parties, which each hosted for the other.So Thursday's appearance was a publicmilestone, even though privately she regularly stays overnight at Charles's London apartments in St James's Palace and at his home in Highgrove, west of London. She has been introduced to both Prince William, 16, and 14-year-old Prince Harry.Opinion has softened on her since Diana's death. The royal-hungry tabloids particularly have toned down their once virulent coverage. ``At last,'' the Mirror triumphed. ``After 26 years, Prince Charles finally declares his love for the woman he has privately adored.''