One would expect the Labour Party to revere Mr Blair as its greatest electoral asset. But the opposite is true.
Mr Blair was more successful as a party leader winning elections than he was as a governing prime minister. His biographer looks at why his standing is so low in his own party and beyond.
It was the former British prime minister Tony Blair's foreign policy, though, that was to produce the biggest controversy of his premiership, including protests in London and across the country.
His support for US President George W Bush in the invasion of Iraq in March 2003 was the most disputed foreign policy decision by a British prime minister since Anthony Eden decided British troops should invade Egypt in 1956.
The manner of Mr Blair's decision was hotly disputed, including question marks over whether he had misled the country to build his case for committing British troops.
He might have been forgiven had the American-led invasion been a success, but its spectacular failure to bring peace to Iraq led to many years of recrimination.
Mr Blair, ironically, enjoyed his most successful period of governing in his final few years in Downing Street, when he had learnt, as he himself admitted, how to manage the job.
But Mr Brown's succession as prime minister in May 2007 could not calm the angst surrounding him.
Thus begins part two of our story, the post-premiership. Mr Blair outlined a very ambitious prospectus for his life after Downing Street. He became the UN's "Middle East Envoy" and worked to bring peace to the Arab-Israeli conflict.
He also had ambitious plans for Africa, for helping world religions to understand each other, and a host of other good causes.
This was an admirable program, which should have earned him approbation rather than opprobrium.
The fact remains though that almost a decade after leaving Number 10, Mr Blair's public standing is even lower.
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