Former glamour model Heather Mills has been accused of cheating on estranged husband Sir Paul McCartney in the early days of their relationship. Mills dated British film editor Tim Steel on and off for three years, but broke off their relationship shortly after meeting the ex-Beatle at an awards ceremony in May 1999. MCCartney and Mills began courting in August that year - but Steel claims the 40-year-old soon started an affair with him and returned to his bed on several occasions while she was being wooed by the singer. Steel says, "I didn't mind (sharing her with MCCartney) - I suppose I was flattered that Heather still wanted to have sex with me despite being pursued by this musical demi-god. "(But) it was strange lying in bed talking about Paul MCCartney. I would be with her when he called or texted her. She'd even show me the texts!" Steel also alleges to have enjoyed a steamy night of passion with Mills less than 24 hours before she was due to fly to the Caribbean to join MCCartney for their first vacation together in 2000, reports British tabloid News of the World. He adds, "I was glad she wanted to stay with me. She was in two minds about him and was wondering if she was doing the right thing. She seemed nervous about this first holiday with him." And he claims Mills consulted him about marrying MCCartney - but was only interested in wedding the star because of the opportunities it would bring her. He adds, "Marriage to him (MCCartney) opened lots of doors for her - and that's the only reason she did it. "...I guess I hung around because I really didn't think Heather and Paul would last. He was an old bloke and I knew what Heather was like. She was only in love with what Paul could do for her. She loved the idea of being Lady MCCartney." MCCartney is currently embroiled in a bitter divorce battle with Mills - the mother of his four-year-old daughter Beatrice - who he split from in May 2006. The former couple are due to fight it out in London's High Court this week (begs11Feb08) after failing to reach a financial settlement out of court.