Alison Sharland, 46, says Charles, 53, convinced her to give up her claim to an equal share when they divorced.
Mr Sharland told her his shares were worth about £7 million but press reports said the company could be floated on the stock market for more than £460 million.
Patrick Chamberlayne QC, for Mrs Sharland, told the Court of Appeal that the marriage had been equal and the divorce settlement was supposed to be the same. “She was cheated into an agreement,” Mr Chamberlayne said. “All the assets had been acquired during the course of the marriage and each party had made their full contribution.
“Part of the wife’s case was that she was busy making post-separation efforts as well. She had the unusual task of lifelong care of the parties’ disabled child.”
Mrs Sharland, who runs an autism charity, and her ex-husband, a farmer’s son, married in 1993. They built a substantial fortune before they separated in 2010, the judges heard. They lived in Wilmslow, Cheshire, and Mr Sharland ran his company from a business park in Daresbury, near Warrington.
On divorce, they agreed the matrimonial assets should be split equally but a dispute arose over the valuation of Mr Sharland’s shares in AppSense.
Accountants instructed by Mrs Sharland put the value at £32 million. Those working for the husband said they were worth only about £7 million after incentive-based disbursements to others.
During the divorce proceedings last year, they agreed to compromise, with Mrs Sharland getting more of the liquid assets, but giving up her claim to an equal share of the company. She got £10.4 million in cash and property and paid less than her husband into a trust fund for their son. She agreed to take 30 per cent of the proceeds of sale of the shares when they were put on the market. Mr Chamberlayne said she based her agreement on the value of the shares being no more than £32 million and on her husband’s evidence that the company would not be floated on the stock market until about five or seven years later.
But it emerged that he had misled her and had been planning an initial public offering of the company while he was in the witness box, the QC said.
Reports in the financial press suggested the price could be more than £460 million, which would mean Mr Sharland’s shares were worth at least £132 million after tax, he explained. Mrs Sharland took her case to the Court of Appeal after Sir Hugh Bennett, the family judge, refused to reopen her claims.
Mr Chamberlayne said it was wrong that, having entered into an agreement on the basis of her ex-husband’s dishonesty, Mrs Sharland was being denied the chance to fight for more of the business.
Mr Sharland does not dispute that he seriously misled his ex-wife, but says the final order made by Sir Hugh was fair.
Appeal judges Lord Justice Moore-Bick, Lord Justice Briggs and Lady Justice Macur reserved their judgment on Mrs Sharland’s appeal until next year.
This story was reported in The Telegraph.