Mark Stephens, a Times Online legal columnist who represented Paula Yates in her divorce from Sir Bob Geldof, said in an interview with ITV that Sir Paul had the most to lose if the fight goes to court.

"I think Heather, if she pushes it, could get up to a hundred million," Mr Stephens said. His assessment was echoed by Max Clifford, the publicist to the stars.

The half-hour documentary, McCartney v McCartney, which appears at 10pm tonight, explores the acrimonious breakup that has preoccupied the nation's tabloids for several months. It claims that Lady McCartney has become "fair game" for publicity since the couple split, with 216 photographs of her published to only 165 of Sir Paul.

The programme hints that the couple may have decided to call a truce. "Last week the couple met face-to-face for the first time in 70 days to acknowledge the PR war has to end," it says.

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