Mr Barrett, a high school dropout from Kerry who rose from an inauspicious start as a junior bank teller in the Bank of Montreal's London branch to become chairman and chief executive of one of Canada's largest banks had decided to quit in February after his attempts to forge a merger with Royal Bank of Canada fell foul of Canadian anti-trust rules.
Although there are few doubts about his abilities as a banker or his aptitude for the Barclays job, he will have difficulty shedding the livewire image which dogged him in Canada and may ultimately have driven him out of this most conservative of countries.
His name was rarely out of the Canadian gossip columns on account of his recently estranged second wife Anne-Marie Sten - a glamorous former companion of Adnan Khashoggi, the Saudi arms dealer. Ms Sten's naked full- frontal figure appears in glorious technicolour on the front cover of the latest issue of Frank Magazine, Canada's answer to Private Eye. Frank Magazine is available on the Internet to those of Barclays employees who care to take a look at what their new chief executive has left behind.
Canadian commentators say that so intense was the media interest in the 54-year-old Mr Barrett and his 43-year-old wife that he found it impossible to be taken seriously when he attempted to lobby the Canadian government about a merger with the Royal Bank of Canada last year.
After his previous marriage failed after 28 years, Mr Barrett, a tall, dashing individual with an unmistakably Irish sense of fun, had been described as the most eligible bachelor in Canada. His first marriage produced four children, one son and three daughters, now aged between 20 and 27.
When Mr Barrett and Ms Sten tied the knot two years ago at what was billed by the Canadian press as the society wedding of the year, Mr Barrett described the event as "a second chance of happiness with a fabulous woman whose heart was the size of a 747".
More recently, when he started turning up at society events unescorted, the tongues again began to wag.
The desire to put an end to the constant publicity was cited as one of the main reasons for his decision last February to leave the bank where he had worked for 37 years, that and the fact that he had invested so much time and energy in the merger and had no fall-back strategy when the deal collapsed.
Yesterday he said of his marriage: "We are separated. I am coming to London on my own. That is all there is to say."
This is the second time that Barclays has turned to North America in order to fill the vacancy left when Martin Taylor, its young, dynamic chief executive quit last December in extraordinary circumstances. Mike O'Neill, the former chief financial officer of Bank of America who was Barclays' first choice as replacement resigned on his first day at his post in April after developing a heart condition following a severe bout of flu.
Eager not to be caught out a second time, Barclays subjected their new choice to a rigorous medical examination, after which Mr Barrett joked that he that "was ready for the Olympics".
Both he and Sir Peter Middleton, the Barclays chairman, were showing the strain of the negotiations which began six weeks ago in earnest and which ended after a Bank of Montreal board meeting at 2am yesterday.
Throughout an interview with The Independent yesterday Mr Barrett repeatedly referred to his new employer as Lloyds while Sir Peter called him Mike.
When Mr Barrett announced his decision to leave Bank of Montreal, the plan was to relinquish the chief executive officer role immediately and the chairmanship in November, leaving him free in the meantime to look for another job.
Bank of Montreal have agreed to let him go in time to start his new job in October.
Mr Barrett had been on Barclays' initial short-list although Barclays did not believe he would be available. But by April when the search for a chief executive resumed in earnest, it was clear that Mr Barrett - who apart from advising the Irish government on the privatisation of the Irish TCC and TSB banks, would soon be at a loose end - had now become open to offers.
Mr Barrett said yesterday that when he started out at Bank of Montreal's branch in the west of London at 18 years of age, he looked "with envy" at the Barclays branch across the road. "Little did I imagine then that I would one day end up running the bank. It is unseemly the excitement that I feel," he said. And on a salary 500 times that of the average Barclays teller.
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