If it is a basic rule of househunting that forced divorce sales are an ideal source of bargains, then Green Lane Farm should have a lot going for it. Not only is its owner, Heather Martin-Dye, obliged to sell up, but she is doing so after a highly publicised legal defeat in the court of appeal that was plastered over the newspapers and declared by her former husband, Philip, as a “triumph for Man”.

Not that Heather, 54, who put her 16th-century Surrey home on the market last week for £5m, can bring herself to admit she is desperate to sell. But in a landmark ruling late last month, she was ordered to pay Philip, 54, £646,000 on top of the original £3m award, plus a share of the costs — money she says she doesn’t have — and the interest is going to start racking up quickly.

“As soon as I got back from the court, I went into the estate agents and asked them to put it on the market for me,” she says, relaxing in her massive drawing room, which looks out onto manicured lawns and the pool and tennis court beyond. “Remarkably, it was the same agent who sold it to me 20 years ago.”

Heather and her children, Isadora, 20, and Freddie, 17, will be loath to go — not least because of the transformation undergone by the timber-framed Tudor manor house in Shamley Green, near Guildford, since she and her first husband, Nick Horgan, bought it for £325,000 in 1984. Situated in 50 acres, it was a comfortable if unspectacular four-bedroom, two-bathroom house, which had been rather nastily modernised in parts with the addition of some large and inappropriate french windows. That all began to change three years later, however, when — with Horgan out of the picture — Philip, a British Airways pilot, moved in.

The couple disagree about his precise status: Heather claims he was a lodger. Philip says he had two homes of his own, one in Ascot, Berkshire, and the other in West Wittering, West Sussex, and merely needed somewhere to stay while the decorators were in. Either way, love blossomed and the couple married in late 1987.

In the years that followed, they spent about £750,000, largely from the sale of a software company Heather had floated, on renovating and almost doubling the size of the house. With Philip masterminding the project, a new wing was built to match the old — making use of old oak recovered from Surrey barns flattened by the gales of 1987. A particular challenge was finding beams long enough to span the 25ft drawing room ceiling.

The result is a spectacular and remarkably authentic seven-bedroom, five-bathroom country house, which also boasts a converted-barn-turned- party room, two four-bedroom cottages, a spacious flat and stabling for 29 horses. Although there is clearly no love lost between the two, Heather grudgingly admits that Philip, who now runs the kitchen business they set up together, did a good job.

So good that the house has been a popular television and film location: the drawing room has doubled for Michael Jackson’s Neverland ranch in the spoof Rock Profile, Silent Witness’s Amanda Burton has walked the lanes outside, while the master bedroom, complete with four-poster bed, featured in an “after the nine o’clock watershed nude sex romp”.

Quite how much the works added to the value of the property has long been a matter of contention between the Martin-Dyes, whose financial wranglings make sobering reading for anyone already married or merely contemplating it.

Three years ago, when it was time to value the house for the divorce, Heather set out to achieve as low a figure as possible, leaving the lawn uncut and flower beds unweeded and encouraging the cottage tenants to hang out their washing across the courtyard. The poop from their many dogs went deliberately unscooped. “The aim was to make it look as shambolic as possible,” she says.

For each unrealistically low valuation that her agent came up with Philip’s produced another, however, and in the end, exhausted by the toing and froing, they accepted an independent valuation by Savills, who settled on £3.2m.

Taken together with other assets — including a five-house estate a couple of miles away in Shamley Green, in which Philip is now ensconced — their combined wealth came to £6.3m, which was divided between them 57:43, in Heather’s favour, in a reflection of the greater value of the assets she had brought into the marriage.

So far, so amicable — at least on Heather’s side. Philip, however, resented the inclusion of his BA pension fund of just under £1m as part of his share of the assets and went to court to assert his rights. And last month, after long legal battles and the inevitable hundreds of thousands of pounds of legal bills, the court of appeal decided in his favour.

In a ruling that could have implications for other divorcing couples, the court ruled the pension pot as such should not be included in the listing of the capital assets, but the couple should instead divide the £37,000 a year it pays out.

This means the total value of assets has to be recalculated downwards — leaving Heather needing to raise a small fortune to pay off her former husband.

It should be possible to do so by selling off the cottages, stable or some of the land, but Heather fears this will undermine the value of the house — and feels the only solution is to dispose of the estate as a whole and downsize. “It’s a wonderful, beautiful home and it’s heartbreaking to leave it,” she says. “But I have no choice.”

Green Lane Farm is on the market with Savills, 01483 796 820, www.savills.co.uk

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