THE former Minister for Transport, Energy and Communications' current problems began on the longest day of the year. On June 21st, 1996, Ben Dunne and his sister Margaret Heffernan lodged affidavits in the High Court.

Ben Dunne is the plaintiff in an action where he is claiming that the valuation of £1 each placed on the shares of his late sister, Therese, is a gross underestimate of their true worth. The defendant in the action is Ms Heffernan, who ousted her brother as chairman of Dunnes Stores in a boardroom coup in February, 1993.

The bitterness between them stemmed from an extraordinary incident in Florida the previous year. But the outcome of the present litigation is more about Mr Dunne's exposure to tax liabilities than the family feud, according to accountancy sources.

To describe Mr Dunne's business methods as unorthodox is scarcely an understatement. He would fly suppliers and customers to golf courses in the United States, all expenses paid. However, the deal included wagers with Mr Dunne on a scale which Mr Dunne could afford but his fellow players could not.

THERE were other draw backs. Mr Dunne's recreational lifestyle in Florida, made headlines when he was charged with cocaine trafficking in an Orlando court in February, 1992. He denied having attempted to commit suicide by trying to jump from the 17th floor of the Hyatt Regency Grand Cypress Hotel in Orlando.

A woman who was in Mr Dunne's room at the time was treated for a drugs overdose. Orlando police said, she was an employee of a local "Escorts in a Flash" agency.

In May, Mr Dunne did not enter a defence to a charge of possession of two grams of cocaine. The prosecution dropped the more serious charge of drug trafficking. The court in Florida ordered Mr Dunne to undergo a period of residential evaluation and treatment for drug abuse in a London clinic.

In retrospect, it may appear that, Mr Dunne got off lightly. However, his reputation within the family business was fatally undermined.

His business dealings with associates such as Mr Lowry, owner of Streamline Enterprises, had been conducted more or less as Mr Dunne saw fit. His sister, Ms Heffernan and his brother, Mr Frank Dunne, decided this could not continue.

Their elder brother could not be allowed to sign large cheques at his own discretion without reference to other board members. They eventually persuaded another sister, Therese, to join their camp. The board voted to dismiss Ben Dunne as chairman.

HE remained with the company for a year with specific responsibilities determined by the board.

However, he openly declared his support for his wife Mary's plan to open a store in Finglas which would compete inter alia with a nearby Dunnes Stores outlet. Nobody was in much doubt that her husband was the real force behind the move.

He further antagonised the family firm by paying £900,000 for a 75 per, cent stake in the publicly quoted Dunloe House, which owned 15 shops in the Merrion Shopping Centre in Dublin and could, at least in theory, be used as a vehicle to compete with the company which was employing him.

The inevitable happened in November, 1994. He sold his Dunnes Stores shares for a rumoured £100 million. The payment was to be made over a number of years. However, in the course of the court battles - where Mr Dunne was represented by the present Attorney General, Mr Dermot Gleeson - Mr Dunne described the Dunnes family trust, set up by his father in 1964, as a sham, a claim which was bound to arouse the interest of the Revenue Commissioners.

The Revenue would also be exercised by the terms of Mr Dunne's share sale. Estimates of his tax liability range between £24 million and £35 million the largest, potential liability for an individual in the history of the State. Under capital gains tax, Mr Dunne was facing a bill of 40 per cent on the difference between the value of his interest in the trust at the disposal date and the value of his stake when the trust was set up, indexed to present day values.

If his settlement came from the Dunnes trust fund assets, Mr Dunne could also be liable for gift tax at a rate of 75 per cent of the inheritance tax rate of 40 per cent at an effective tax rate of 30 per cent.

The bottom line for Mr Dunne now is that the latest stage of his litigation against his sister, which began last June, is to protect his assets from the taxman. Michael Lowry's tax affairs, which have come to light as a result, are in financial terms a mere sideshow.