Sir Paul McCartney is reportedly romancing heiress SABRINA GUINNESS, a former girlfriend of British royal Prince Charles and fellow rocker SIR Mick Jagger. MCCartney - single since his split from Heather Mills last year - and 52-year-old Guinness were spotted meeting in secret in London on Wednesday night (21MAR07). The former beatle, 64, picked up Guinness at her Notting Hill home, but when the pair realised they had been spotted by photographers, MCCartney dropped her off at a friend's house and met daughter STELLA at an Italian restaurant instead. According to friends, the couple have enjoyed a number of dinner dates and Guinness is helping MCCartney get over his split with Mills. A source tells British newspaper The Sun, "His friends are desperate to get him out and about and to start living again. "People like Sabrina are making this possible." Guinness has never married, but during the 1970s the heiress to the Guinness drinks empire was linked with a string of celebrities including Jagger, Bryan Ferry, Jack Nicholson and Michael Douglas. During her relationship with Prince Charles she was even touted as a future Queen of England.