The doctor has given his verdict. Tony Blair’s vaulting arrogance over Iraq showed an extreme case of hubris, according to Lord Owen, the former foreign secretary and neurology specialist.

In a new analysis of the former prime minister’s psyche, Owen argues that, starting with the Kosovo war of 1999, Blair gradually tipped into “excessive self-confidence, restlessness and inattention to detail”.

Owen likens Blair’s symptoms to the hubris of ancient Greek drama in which a taste of success brings excessive arrogance in the hero. He loses a sense of reality, blunders and is destroyed.

Owen, 69, writes that Blair deteriorated from relative normality at the start of his premiership. After September 11, 2001, he had the “ring of zealotry”. Blair, now fighting climate change and waging peace in the Middle East, embarked on a “frenetic” world tour. Later, his blithe dismissals of any difficulty in the run-up to the Iraq invasion in 2003 became extreme.

“This was not ordinary incompetence, it was hubristic incompetence,” writes Owen in his book In Sickness and in Power: Illness in Heads of Government, an extract of which appears in today’s Sunday Times News Review. Owen, foreign secretary from 1977-9, uses his book to analyse some of the psychological conditions affecting the decisions of world leaders over the past century.

The diagnosis of Blair’s failings may bring a smile to Brownites – the current prime minister was once described by aides of his predecessor as “psychologically flawed”.

Owen’s interest in political psychology dates from when he was a young medic at St Thomas’s hospital, over the Thames from parliament; MPs used to visit doctors there for therapy.

Times Recommends

• New York threatens London's place in fashion
• Computer game to rewrite evolution
• Teacher shows how to live on £1 a day