Golfer Colin Montgomerie sues ex over 'unfair' post-nup

Golfing legend Colin Montgomerie is suing his estranged wife for £5 million, over what he claims is an unfair post-nuptial agreement.

He and wife Gaynor, 50, split up in 2015. Colin, 53, has admitted that he had cheated with another woman - and had signed a post-nuptial agreement in 2010.

Most of the details of the case can't be reported for legal reasons, but Montgomerie is now disputing the fairness of the agreement and is seeking £5 million.

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The row highlights the uncertainty over post-nuptial agreements in the UK.

Post-nups are agreements between couples who are already married or in a civil partnership and, like pre-nups, set out the way that their assets and income will be divided in the event of a split.

They're most used in second marriages where there are children involved, or to protect inherited wealth or the ownership of a company. But couples also often turn to them when a new child is born, a new company is founded, or when one of the couple receives an inheritance.

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Again like pre-nups, these agreements aren't legally binding. There has, though, been a trend to give weight to them in the courts - as long as certain conditions apply.

"The courts are increasingly aware of the importance of upholding marital agreements, and the courts will follow an agreement unless there is a good reason to deviate from it," says Jayne Chilvers, a partner with law firm Nelsons Solicitors.

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The guidelines say that both parties must enter into the agreement of their own free will, without any pressure, and both must understand the implications of the deal. Both must also disclose all relevant information.

In a landmark case a few years ago, the Supreme Court concluded: "A Court should give effect to a pre-nuptial agreement that is freely entered into by each party with a full appreciation of its implications unless, in the circumstances prevailing, it would not be fair to hold the parties to their agreement".

In this particular case, the decision is likely to hinge on that 'fairness'.