Britain's ambassador to Dublin once warned that former Taoiseach Charles Haughey was a man of "calculating and ruthless ambition", according to newly declassified files.
A candid diplomatic despatch for 10 Downing Street ahead of Mr Haughey's first face-to-face meeting with British Prime Minister Margaret Thatcher in May 1980 described the Taoiseach as having a "taste for the good things in life" but few real friends.
The UK's then-ambassador to Ireland, Robin Haydon, painted a picture of a former heavy drinker who had become a "puritan" in recent years and all but given up alcohol and tobacco, documents released by the National Archives show.
He wrote: "His predominant characteristic seems to be a calculating and ruthless ambition: there is no secret that the office of Taoiseach has been the over-riding objective of his life. He seems to have few real friends but appears to surround himself with a close-knit and faithful coterie of associates, whom he dominates by force of character."
In a reference to the notoriously lavish lifestyle and fishy finances of Mr Haughey, whose three terms as Taoiseach between 1979 and 1992 were dogged by controversies such as allegations of corruption and gun-running charges, Mr Haydon said the Irish premier's fortune came partly from speculating on property while he was finance minister.
The ambassador said the Taoiseach collected pictures and antiques furniture, owned racehorses and enjoyed riding with hounds, had a "showplace" house and was "immaculately turned out".
He concluded: "To sum up, I think he is a tough, clever, wily man, no friend of ours, but not, perhaps, actively hostile. He is conscious of his shady past (and present!)."
The meeting between Lady Thatcher and Mr Haughey in London on May 21, 1980, was considered a big success on both sides, the documents show. The British prime minister rang him the next day to thank him for the "beautiful" teapot he gave her as a gift.
Mr Haughey replied: "You were very gracious and wonderful hospitality and a delightful atmosphere, and it was a most satisfactory day indeed for us."
The Irish premier also told Mr Haydon he was "most impressed" by Lady Thatcher and thought the atmosphere at the lunch the two leaders shared was "wonderful".