An ageing farmer who spent nearly 50 years building up a thriving business is now locked in a bitter court battle with his son over the carve-up of a £2m Somerset estate.

The farming business established by Ronald and Jean Ham represented their “life’s work”, London’s Appeal Court heard, having started out in 1966 on a modest 5ha plot before buying a 90ha site at Lower West Barn Farm, Witham Friary, Frome, in 1986.

By 1997 the farm had expanded to 178ha, and soon afterwards the couple decided to bring their son, John, into their partnership.

The couple’s barrister, Nathaniel Duckworth, said the farm was “their only source of income” and represented their “eventual legacy to their children”. They hoped their son would one day take over the mantle and continue the farming tradition Mr Ham had inherited from his own father.

John, now 34, stepped into the business at the age of 19, the court heard, and had worked industriously alongside his parents.

His barrister, Ian Partridge, said he had worked “long hours with youth and vigour for over 11 years” and insisted that the pay-out envisaged by his parents was “not overly generous”.

Mr Partridge said the case would result in a “manifest unfairness” to John as he would be denied a share in the full value of the agricultural land.

John’s sister, Catherine, had also helped out on the farm, left when she married 16 years ago.

However, by 2009, the three-way working arrangement between the couple and their son had begun to unravel, said Mr Duckworth, resulting in John’s fateful decision to “retire from the partnership”.

The current acrimonious dispute between John and his parents centres on his claim that he is entitled to the full market value of his share in the family business.

In court, Mr Duckworth said this would represent a “game over” scenario for his parents since they would have to find a six-figure sum to pay John, or else sell off a large part of the farm.

Mr Ham senior, 73, was in court alongside his wife as lawyers on both sides debated the crucial issue in the case – whether John’s share should be assessed on the “book value of the estate” or on its current market value.

The “book value” route would result in a far more meagre pay-out for John as it would ignore the soaring land value of the family’s 178ha, and instead focus on the worth of fixed assets like the dairy herd and other livestock.

The family’s vexed dispute reached the Appeal Court last week as John challenged a Bristol County Court ruling in March, which declared that his share of the partnership should not be assessed on an “open market basis”.

The Appeal Court – comprising Lord Justice Rimer, Lord Justice Lewison and Lord Justice Briggs – reserved their decision on his appeal and will give its ruling at an unspecified later date.

After the hearing, Mr Ham senior told reporters: “If you’re in farming, don’t go into partnership with your son”.

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