Bob Diamond has long faced criticism for his high pay, being described as "the unacceptable face of banking" - but in the end he was brought down by a politically toxic rate-fixing scandal.

Diamond, born in the United States, was a high-profile figure who drew admiration from many in the industry for making Barclays a global player in investment banking.

But the row which ultimately led to his departure has prompted a chorus of condemnation, amplified by deep public suspicion of Britain's banking sector, all but obscuring that achievement.

Richard Branson, perhaps Britain's best-known businessman, described Diamond as a "great banker" following his resignation.

"He built Barclays into a formidable bank and it is sad to see what has happened at Barclays," said Branson.

"I think the banks have just got to turn over a new leaf," added the entrepreneur whose Virgin Money business last year bought British bank Northern Rock, nationalised at the height of the global financial crisis in 2008.

Diamond, aged 60, who started his career as a lecturer at the University of Connecticut's business school, took over as chief executive of Barclays in January 2011 and served only 18 months before quitting.

Before that, he was head of the bank's investment banking arm, Barclays Capital, at the time of the suspected manipulation of inter-bank lending rates.

Here, Diamond played a key role in negotiating the $1.75-billion purchase of Lehman Brothers' US investment banking and capital markets operations after the Wall Street giant's collapse during the 2008 financial crisis.

Diamond became one of the world's highest paid bankers, earning £17.7-million (22-million euros, $27.7-million) in salary, bonus, benefits and long-term share awards last year.

Widely reported to be the best-paid chief executive of a FTSE 100 company, he was reportedly in line to receive £11-million this year before waiving his bonus.

But his high earnings were the subject of fierce controversy, while he was seen by many to embody a bonus culture unpopular with the British public during the economic downturn.

Former business secretary Peter Mandelson in 2010 referred to Diamond as "the unacceptable face of banking."

Mandelson told The Times newspaper that Diamond had "taken £63-million not by building business or adding value or creating long-term economic strength, he has done so by deal-making and shuffling paper around."

But Barclays described that figure as "total fiction".

Diamond himself has battled to dispel his portrayal by parts of the media as a greedy gambler.

Last year, he described how he had introduced a "no jerks rule" to weed out bankers he considered too greedy or ostentatious.

In an interview with The Times newspaper, he said he had kicked out between 30 and 40 staff who broke the rule in an effort to foster a more socially responsible culture.

"If someone can't behave with their colleagues and can't be part of the culture, it doesn't matter how good they are at what they do, they have to be asked to leave," he said.

Painting himself as a man with modest tastes, he said he used budget airline easyJet rather than a private jet and prefered chain pizza restaurants to Michelin-starred establishments.

Diamond previously defended Barclays over claims it indulged in "casino banking" - a term commonly used to describe the high risks taken by investment bankers.

In comments to the Sunday Telegraph newspaper in 2010, Diamond said that the term "has no basis in reality."

He said: "These aren't casino businesses. These are real, client-driven businesses."

British finance minister George Osborne welcomed Diamond's resignation on Tuesday, which came the day after that of chairman Marcus Agius and hours before chief operating officer Jerry del Missier quit.

I think it's the right decision for Barclays and I think it's the right decision for the country," he said.

"I hope it's a first step towards a new culture of responsibility in British banking."

Barclays says the size of Diamond's severance package is still under discussion.