LONDON (Reuters) - There is only one winner in a power struggle involving John McFarlane, the banking and insurance veteran who became Barclays (>> Barclays PLC) chairman in April and fired the bank's chief executive on Wednesday.

McFarlane, a 68-year-old Scot, has built a reputation as one of the City's toughest chairmen, with the stomach to make tough decisions and act quickly if a business is underperforming.

During CEO Antony Jenkins' three-year stint as chief executive, the British bank's share price had lagged rivals.

Jenkins had made progress in restructuring the bank and running down 75 billion pounds ($115 billion) of assets it no longer wants, but some shareholders had wanted faster change.

A senior executive at insurer Aviva (>> Aviva plc), where McFarlane previously oversaw a major turnaround, said Jenkins' swift departure was unsurprising given the Scot's track record.

"I think he had made his mind up about Jenkins before he even joined, and the way he's started at Barclays is exactly in line with what happened at Aviva," the executive said.

At Aviva McFarlane played a central role in the removal of Chief Executive Andrew Moss, stepping in to take over the day-to-day running of the business after delivering a damning assessment of Moss's five years in charge.

McFarlane said on Wednesday he made the decision that Jenkins must leave in response to ongoing concerns over his management style and that Jenkins had "acted professionally" when told of his fate last week.

Industry sources say the pair had failed to develop a rapport.

"McFarlane is quite a dominant character and Jenkins is stubborn and doesn't play the internal game so I can well understand why they haven't hit it off. The new CEO will have to be more compliant," one Barclays' shareholder told Reuters.

McFarlane told reporters he was in no rush to appoint Jenkins' successor, setting his stall out to take day-to-day control, just as he did at Aviva.

McFarlane, who began his career with the Ford Motor Company, was chief executive of Australia and New Zealand Banking Group (>> Australia and New Zealand Banking Group) for ten years until June 2007 and has also held senior positions at Standard Chartered and Citibank.

His decision not to appoint an acting chief executive illustrates the confidence he has in his own ability to do the job. Interviewed by Reuters in November 2013, he described himself as one of less than a dozen individuals globally that have the skills to chair a major British bank.

His peers within the industry seem to share that assessment.

"I think John McFarlane is an outstanding professional and I have thought that for many years. He will impose discipline and clarity," said a senior executive at another major British bank.

Industry sources say that McFarlane has developed a strong relationship with Finance Director Tushar Morzaria in recent weeks, and will work closely with him and other senior executives such as Chief Operating Officer Jonathan Moulds.

"He takes time to get under the skin of things, to get to know people and form opinions. As interim CEO, he'll have the perfect chance to get his head under the bonnet," the Aviva executive said.

McFarlane will need to quickly address some major challenges including a requirement for the bank to separate its UK retail business from riskier activities to meet new regulations.

The bank must also resolve allegations over alleged past misconduct while bringing returns back above its cost of capital and deciding how big to keep its investment banking operation.

(Editing by Elaine Hardcastle)

By Matt Scuffham and Sinead Cruise