A sycophantic narcissist whose 'alarming subterfuge' took us to war in Iraq – top law officer's damning verdict on Tony Blair

Sir Ken Macdonald, who was director of public prosecutions at the time of the invasion, launched a devastating attack on the former prime minister, accusing him of acting like a "narcissist" as he tried to justify his actions.

Mr Blair had exhibited "sycophancy" towards Washington in the run up to the war in March 2003, Sir Ken said.

His intervention came after Mr Blair, who is due to give evidence in the new year to the Chilcot inquiry, defended his actions in a weekend television interview with former This Morning host Fern Britton.

Mr Blair told her it would have been right to have invaded Iraq even if it was known then that Saddam Hussein did not have weapons of mass destruction. The threat posed by Saddam to the wider region meant it was right to remove him from power, he said.

But Sir Ken dismissed Mr Blair's attempts to defend his behaviour, saying: "This was a foreign policy disgrace of epic proportions and playing footsie on Sunday morning television does nothing to repair the damage."

He said the US administration had "turned his head and he couldn't resist the stage or the glamour that it gave him".

He went on: "It is now very difficult to avoid the conclusion that Tony Blair engaged in an alarming subterfuge with his partner George Bush and went on to mislead and cajole the British people into a deadly war they had made perfectly clear they didn't want, and on a basis that it's increasingly hard to believe even he found truly credible."

Sir Ken – who works at the same law chambers as Mr Blair's wife Cherie – added: "Since those sorry days, we have frequently heard him repeating the self-regarding mantra that 'hand on heart, I only did what I thought was right'. But this is a narcissist's defence, and self-belief is no answer to misjudgment – it is certainly no answer to death."

Sir Ken claimed the questioning of the Chilcot inquiry panel had been "unchallenging" so far, adding: "If Chilcot fails to reveal the truth without fear in this Middle Eastern story of violence and destruction, the inquiry will be held in deserved and withering contempt."

Defence Secretary Bob Ainsworth, who was deputy chief whip at the time of the war, said at the weekend the government could have lost the vote over Iraq if more had been known about the lack of intelligence on weapons of mass destruction (WMD).

He refused to say if he would still have backed the war, but added: "I supported the war in Iraq based on the arguments that were put at the time, and a big part of those arguments was – and I firmly believed that they existed – the existence of WMD at that time."

Angus Robertson, the SNP's Westminster leader, said it was too late for the government to show regret over the war, and he called for Gordon Brown also to be quizzed by the Iraq inquiry.

"Revelations over the war in Iraq are proving no-one can believe a word Labour says about anything any more," he said.

"Their now discredited lies about weapons of mass destruction were just a front. Blair was Bush's poodle – entering an illegal war for oil, not international security, and doing so against the will of the people.

"Tony Blair took us to war on a false prospectus, and Gordon Brown bankrolled it – both men should appear side by side when they give evidence."