In the latest of his weekly columns for the BBC News website, John Simpson looks at how the decision to go to war with Iraq still dogs the British prime minister.
Testing times ahead for Mr Blair?
Everything should be going so well for Tony Blair. The pre-election campaign seems mostly to be about the troubles in the Conservative camp, the opinion polls are favourable to Labour.
Yet decisions his government took more than two years ago, in the run-up to the invasion of Iraq, simply refuse to go away.
It's not simply a question of the advice which the Attorney-General, Lord Goldsmith, gave the government about the legality or otherwise of fighting a war without explicit UN backing. Nor is it about whether, how and why that advice might have changed.
It goes wider than that; so wide that one of Britain's leading constitutional experts, Professor Peter Hennessy, maintains the decision to join the American invasion of Iraq in March 2003 represented the worst break-down in Cabinet government since the Suez crisis of 1956.
A new element has now entered the debate. Discreetly, various retired Whitehall mandarins have been coming out of the deep cover that they usually inhabit.
People of the quality of Lord Butler, Sir Stephen Wall and Sir Michael Quinlan - a former Cabinet secretary, a former foreign affairs adviser to Downing Street and a former head of the Ministry of Defence - have spoken publicly about the issues surrounding the invasion.
Britain's top civil servants see themselves, rightly, as the guardians of the constitution. They are men and women of considerable rectitude: the last bastion of an older, uncorrupted political tradition.
Take Stephen Wall, for example: a man of such impenetrable discretion that, although you might meet him socially any number of times, you would never dream of asking him a leading question about his job, even now.
Yet during the last week or so Sir Stephen has appeared twice on television, talking about the issues involved in the decision to invade Iraq.
Were mechanisms of government wrongly used in persuading the public to support the invasion?
At no point did he question the Blair government's decisions: that is not a matter for civil servants. But the way in which these decisions were taken was obviously something he had thought about deeply. And it looked very much as though he wasn't happy about it.
Lord Butler's famous report on the role of intelligence in the run-up to the Iraq invasion was, if you read it carefully, a devastating piece of work.
It was carefully and thoughtfully written, and there were few pithy sentences in it which could easily be quoted; as a result, some of Britain's famously less reflective newspapers at first called it a whitewash.
It was nothing of the sort. Properly read, it seemed plain that Lord Butler felt intelligence had been wrongly used by the Blair government.
So were the mechanisms of government wrongly used in persuading the British public to support the invasion?
Last week's 'Panorama' on the government's pre-invasion decisions contained one particularly startling accusation: that Sir Richard Dearlove, the head of MI6, had warned Tony Blair that the intelligence about Saddam Hussein's weapons of mass destruction was distinctly sketchy.
When the intelligence was rendered down for public consumption, whatever question-marks had been added in by Sir Richard were very firmly erased by the government.
The British people were given the impression that British intelligence believed Saddam really could summon up a WMD strike in 45 minutes; and that if necessary his sons could do it for him.
We now know, of course, that neither of these things was in any way true. The WMDs, over which Sir Richard's question-mark hung, didn't even exist any longer.
When Andrew Gilligan famously went on the Today programme after the invasion and said the government had knowingly published wrong information about the WMDs, that seemed to be the weakest part of his and the BBC's case; and this lay at the heart of Lord Hutton's remarkable criticism of the BBC when he made his report.
Yet if Sir Richard Dearlove did indeed warn Downing Street that the intelligence was open to question, and Downing Street took no notice, then Gilligan didn't really get it wrong at all: though he didn't know that at the time.
And, as everyone now appreciates, he was pretty much right about the rest of the non-existent WMDs.
If the way in which the Cabinet decided to get involved in the Iraq invasion is still in dispute, so even more is its method of selling them to a sceptical public.
Lord Goldsmith said Iraq war was legal
The selling process, otherwise known as spin, may have got the Blair government into even worse difficulties than the original decision.
Of course, successive governments, Conservative as well as Labour, have all used spin: sometimes outrageously. But the Blair government has been better and more efficient at it.
Much to the dislike of many Whitehall mandarins, Alastair Campbell, as the head of information, became one of the most powerful figures in the government.
He may be gone, but his system is still in place. Downing Street, for instance, maintains an information officer in Baghdad, who liaises with the Iraqi government.
Recently, on British domestic television news, I reported receiving official Iraqi figures which showed that Coalition forces were responsible for the majority of civilian deaths.
The next day the Iraqi government disputed the figures we'd been given, and the BBC apologised.
But the trouble with spin is that its effects are temporary. It may get you through your current problems, but it can't keep unpleasant realities at bay for ever.
And those realities have a nasty habit of coming back when you least want them.
If you would like to comment on John Simpson's article, please send us your views using the form below.
A few questions have been puzzling most people I know for two years now. The pretext for war was such blatant nonsense, why did Tony Blair pretend to believe it when he could see no one else did? What was his motivation for dragging us into this disaster anyway? And when is he going to apologise to Andrew Gilligan, the BBC, Dr Kelly's family and the people of Iraq?
Janet Wright, London, England
In my opinion people are wrong in their thinking that Tony Blair supported George Bush. In fact everything he did was to portray himself as world leader in which he miserably failed. He has created a lot of enemies around the world. You will hardly find any country in the world in support of the USA. Britain had more respect throughout the world, especially in the Middle East.
It will not be easy for Mr Blair to come out of Iraq mess he has created. My sympathies go to our troops who are fighting "a war for no cause"! I hope Tony Blair will stop being so 'big headed' and will come to his senses.
Mirza M. Kazim, Luton, England
John Simpson's views are always mature and well considered. In hindsight, the invasion of Iraq was a gigantic error. Whether Tony Blair was tempted by publicity or the opportunity of assuming a global role, when he backed Bush, may only be known to him but the result is a once secular and quiet country changing to assume a far more dangerous and globally terror supporting role. The world is worse off after the Iraq invasion.
Dileep Deshpande, El Jadida, Morocco
Mr Simpson, thank you for being so blunt about all this. Tony Blair is indeed haunted politically by his decision to take the UK to war. But I think it will haunt him for a very long time.
Catherine Greene, London
The prevalent view from "across the pond" now is that Mr Bush was bent on regime change in Iraq and that his team "cherry-picked" the intelligence to justify his decision. Mr Blair, being more intelligent than Mr Bush, should have urged caution. Instead, he joined Mr Bush in a rush to judgement, perhaps dreaming of the oil fields of Basra.
L. S. Carrier, Asheville, NC, USA
I think a wedge is being driven between the US and the UK by this action. The UN was at fault for the Iraq problem. I and many like us feel the UN needs a change!
Andrew Gustafson, Chandler, AZ, USA
Once again Mr Simpson is making the mistake of attempting to close the stable door after the horse has bolted. The issue of whether the war in Iraq was legal, warranted or justifiable is no longer relevant to the situation in Iraq today. I would suggest his efforts would be better spent investigating how money is being spent in Iraq, whether oil money is being exploited by the Americans and getting some sort of timetable for the withdrawal of coalition troops.
Malcolm Parker, Basingstoke, England
In the past I have studied international affairs and attended seminars in the USA surrounding foreign policy decisions. Even if mistaken in the past, they have always been made carefully, with input from highly intelligent people. But in the case of Gulf War II, I simply couldn't understand the build up to war, and found it even more astonishing our own Prime Minister jumped feet-first into it. The only justification I could grasp onto at the time was that our government knew something very sensitive that it couldn't reveal - and that this was the justification. But it seems it knew virtually nothing. I am as puzzled as ever - in my opinion this was possibly the worst foreign policy decision made by any major country in living memory - perhaps ever!
Nicholas J. Allen, London, UK
I am all for articles like this - articles that keep needling away at politicians who arrogantly think they know more than their advisers, and that they can make better decisions on their own without listening to experts or public opinion.
Richard Tait, Llanilltyd Fawr, Wales