Heather MillsHeather Mills has reportedly told friends she’s going to hire investigators to prove that Paul McCartney is worth more than the £400million that he claims.

In the former couple’s divorce battle, Heather claimed the former Beatle was worth £825million but Mr Justice Bennett claims he found “no evidence” that Paul was worth more than £400million. Because of the lower level of his fortune, the judge ruled that Heather wasn’t entitled to anywhere near as much of the £125million that she desired and that she should only receive around £35,000 a year in child support for her daughter Beatrice.

Now Heather is said to have told friends she’s going to employ a team of forensic accountants to examine Paul’s finances and try to press for more money. A source told the Daily Mail that Heather’s accountancy firm were refused access key information about Paul’s assets during the divorce case but now she’s ready to hire a new, more diligent team to investigate his music rights, business assets and claims that he’s given money to his other children as a way of hiding it.

Philip Beresford, who compiles the Sunday Times Rich List, told the newspaper: “All I would say is that we were surprised that the valuation of the music rights and business assets were so low.”

“Also we wonder what has happened to Linda McCartney’s money - she was worth some £150million when she died.”

“Obviously it is in the interest of his accountants and himself to keep the figure as low as possible.”

Heather is also planning to prove that £35,000 a year is not enough for Beatrice’s living costs: “Heather says she can prove the amount of money that is being given to look after Bea will not last over the year. She is putting it to the test.”

“Even with Bea travelling in economy Heather says it’s not enough. She is keeping every receipt - including her invoice to her security team - to show that £35,000 is just not sufficient.”

“Heather’s thinking is that Bea should not be seen to have a different lifestyle when she is with Heather compared to Paul - and she is going about proving that is not possible.”

“Heather is hoping Paul will discretely make a payment to her annually rather than want to go back to court and rake all this up again.”

But a legal source added: “Mr Justice Bennett made the ruling based on Heather’s need and also based on the standard of living the couple enjoyed when they were together.”

“It is quite possible that even if Heather proves that Paul was worth £800million, it would not greatly affect the ruling. It is certainly not a given that she would even be granted leave to appeal.”