Charles Haughey used advance notice of the devaluation of sterling to tip off wealthy friends who made a fortune on the stock markets, according to Eamon Dunphy's new book.
The former footballer and political columnist reveals how Haughey likely made money from his inside knowledge, and bought the impressive Abbeville mansion just over a year later.
In his autobiography, 'The Rocky Road', which is released today, Dunphy details the corruption that surrounded the former Taoiseach, who died in 2006.
In the 1980s, Dunphy had moved on from only writing about sport, to also being a controversial columnist dealing with political affairs.
A regular in the Horseshoe Bar in Dublin's Shelbourne Hotel, he rubbed shoulders with the movers and shakers of the time.
In particular, Dunphy reveals how a source "close to Haughey" explained to him how the politician had been able to buy the Abbeville mansion and estate in Kinsealy, north Dublin.
This source told Dunphy that Britain's sterling devaluation in 1967 was the moment when Charlie landed his first big "touch".
In the book, Dunphy writes: "The Irish pound was linked to sterling, so when Harold Wilson's government decided to devalue on November 18, 1967, the Irish government was given twenty-four hours' notice.
"Charlie was Minister for Finance. He passed the information on to a small group of wealthy Irish businessmen who made a fortune on the currency markets.
"They 'looked after' the Man of Destiny who'd tipped them off.
"A year later, with the heat off, Charlie began negotiations to purchase Abbeville, the mansion of his dreams.
"In 1969, he moved from his semi-D in the modest suburb of Raheny."
The Haughey family lived at Abbeville for 35 years, but it was sold in 2004 to Manor Park Homebuilders for €45m.
However, the company has been in the process of being wound up, and therefore the property was placed on the market by the receivers, Kavanagh Fennells.
Earlier this month, Abbeville went 'sale agreed' under an 'exclusivity agreement', with the sale price understood to be about €3m.
The property needs a substantial investment to bring it up to modern standards, and the house needs to be entirely rewired and replumbed.
Dunphy concludes that the story of Haughey's turn of fortune "was known around the town".
"A vigilant police authority or Revenue investigator, might have made an attempt to follow Charlie's money trail," he writes.
"But this was Ireland, the Land of Saints and Scholars, the fiefdom of the Soldiers of Destiny, whose founding father, the thief, Eamon de Valera, was still president and head of State.
"Haughey, Dev's political offspring, was untouchable."