The woman, a former teacher, denied claims made by her husband that the couple had set up the trust for the benefit of their two children, according to reports in the UK’s Evening Standard.
A High Court judge has now ruled against her, concluding that the trust was “not a sham”.
The judge said the dispute about the legitimacy of the trust was one of a number of preliminary issues she had ruled on during the pair’s divorce battle.
The judge added the woman would have been able to make a claim for half of the couple’s £60m fortune, but was now looking at a half share of £10m.
Detail of the case emerged in a ruling produced by Justice Robert, who urged the couple to negotiate after racking up lawyer’s bills of more than £2.2m.
She said both were in their 50s and had built up a property investment portfolio after marrying in the early 1980s.
Justice Roberts said at one stage, the wealthy couple owned a house overseas which had a swimming pool and a private chapel.