Nobody can dismiss this vast document as a whitewash.

In temperate language, without calling for war crimes trials or public executions of guilty men, the Chilcot Report describes how almost every arm of the British body politic abjectly failed in its duty before, during and after the Iraq conflict.

If the authors sometimes decline to pass explicit judgments, they provide devastating evidence to enable us to do so.

In the minds of the inquiry’s members, among the foremost of their responsibilities was compilation of an exhaustive documentary record, which goes far to explain why the report took so long.

Of course, Tony Blair’s role will attract most public attention, and so it should.

Tony Blair’s role will attract most public attention, but the Westminster and Whitehall also made failings

The exhaustive inquiry chaired by Sir John Chilcot delivered a damning verdict on the Iraq conflict

Families of soldiers that died in the Iraq war gathered in London to hear the evidence against the establishment

What took place was only possible because in 2002-3 Blair was an immensely popular Prime Minister with a personal dominance that enabled him to persuade or conscript the rest of Westminster and Whitehall to support an Iraqi adventure overwhelmingly driven by his own hubris and moral fervour.

From an early stage in 2002, Blair gave private assurances to President Bush that he was eager to back an invasion of Iraq.

In this he fell victim to that eternal curse upon British Prime Ministers — a desire to play partners with the United States, in the utterly mistaken belief that this will buy Britain leverage on other issues.

Here is a critical sub-text of Chilcot, who writes acidly that the UK-U.S. relationship does not require Britain to give ‘unconditional support’ to the Americans.

Yet Blair made the fatal error of acquiescing unconditionally in the Bush White House’s timetable for military action early in 2003.

Throughout, Bush played Blair like a hooked fish. The result, as Chilcot says, is that ‘the UK chose to join the invasion before the peaceful options had been exhausted’.

Attorney-General Lord Goldsmith refused to rule on legality of the war. The report says only a court of law could pronounce on this

Joint Intelligence Committee chairman John Scarlett was rewarded with the directorship of the Secret Service

Did Blair, then, lie to Parliament and to the British people about the threat posed by WMD, to justify a deal he had already made? The report is inconclusive on this critical point, because the authors believe they could not convict the Prime Minister of deliberate untruth, because there is no evidence that he knew WMD did not exist.

What they do show, however, in devastating detail, is that Downing Street became enthralled by fantasies about WMD, to which no reasonable person could have succumbed — unless he was a British Prime Minister already privately committed to supporting an American President.

The Secret Intelligence Service and the Joint Intelligence Committee come out of the story as deplorably as they deserve. Both utterly failed in their responsibilities.

Sir Richard Dearlove then director of the Secret Intelligence Service (pictured)

The charges are grievous indeed against Sir Richard Dearlove, then director of the Secret Intelligence Service — who, grotesquely, went on to become master of a Cambridge college dedicated to truth and learning — and Joint Intelligence Committee chairman John Scarlett.

Scarlett’s rightful role was to serve as a cool, impartial and sceptical arbitrator of the pre-war intelligence story. Instead, he allowed himself to be co-opted onto the Downing Street team making the case for the war.

Blair afterwards rewarded him with the directorship of the Secret Service, a role for which his credentials compared unfavourably with those of Pinocchio.

Scarlett is today a familiar jolly presence on the London party scene and an independent director of The Times, when he should rightfully be running a whelk stall on St Helena.

Chilcot, nuanced as ever, does not find Dearlove and Scarlett guilty of deliberately fabricating evidence to justify Blair’s war, but instead of something as grave, and more cowardly. They stood by in silence, while Blair made statements to Parliament and the British people about the threat posed by Saddam Hussein which both of them knew to be wholly unjustified by the facts.

One egregious example of this was when Blair told NBC News on April 10, 2002: ‘We know that [Saddam Hussein] has stockpiles of major amounts of chemical and biological weapons.’

Blair throughout presented WMD evidence, in Chilcot’s words, ‘with a certainty that was not justified’.

The proper function of the intelligence services is not to serve as operational tools of the Prime Minister of the day: it is to provide impartial reporting.

The only spooks to emerge with credit are those of MI5, whose chief Eliza Manningham-Buller warned repeatedly that, far from an invasion of Iraq making Britain a safer place, it would instead render it a more dangerous one, a prime target for Muslim extremism, as indeed it has proved.

Next among the guilty men is Lord Goldsmith, the Attorney-General. Chilcot will incur criticism, if not scorn, for his refusal to pronounce on the critical issue of whether the war was, or was not, legal. The report says doggedly that only a court of law could pronounce on this.

What is plain from the evidence given here, however, is that the Attorney-General at first advised the Prime Minister that the legal basis for war was extremely doubtful, if not non-existent, and that later he changed his mind.

From an early stage in 2002, Blair gave private assurances to President Bush that he was eager to back an invasion of Iraq

On July 28, 2002, Blair wrote to Bush: ‘I will be with you, whatever,’ an assertion from the head of the British government that Chilcot notes had been subject to no discussion whatever with colleagues

The government’s law officers are little-known figures, whose function often seems marginal. But there are moments in history, of which 2003 was certainly one, when their role becomes pivotal.

There can be no conclusive answer to the question of why Lord Goldsmith changed his mind, but the most plausible explanation is that he wished to support his chief, the Prime Minister.

This is a deplorable motive for such treatment of an issue of such gravity. Lord Goldsmith emerges from this story with his reputation in tatters. Here was perhaps the only moment of his life at which he was involved with anything really important, and he flunked his responsibility.

I suggest — even if the report does not say so — that on the basis of the evidence provided here, the decision for Britain to go to war in 2003 was illegal.

The next grim failure is that of Cabinet government. Where, amid the fevered diplomacy and dramatic preparations for war, was collective responsibility, Cabinet participation in policy-making?

It may be argued that this is more honoured in the breach than in the observance, even in good times, and especially under powerful Prime Ministers such as Churchill, Thatcher and — yes — Blair.

On the Iraq issue, however, the silence or acquiescence of the Cabinet, the lack of a dedicated Cabinet committee, and especially the complicity and slavish loyalty of Foreign Secretary Jack Straw in Blair’s decision-making, invites disgust.

On July 28, 2002, Blair wrote to Bush: ‘I will be with you, whatever,’ an assertion from the head of the British government that Chilcot notes had been subject to no discussion whatever with colleagues.

Members of the Cabinet served as the Prime Minister’s poodles, without even his excuse that they believed in the rightness of what they were doing.

And now we come to what, to me, is the most distressing feature of the Chilcot Report: its damning judgments on the leadership of the Armed Forces and especially that of the British Army.

The Chilcot Report made damning judgments on the leadership of the Armed Forces and especially that of the British Army

The Armed Forces allowed themselves to enthuse about a project for which they were woefully, shamefully ill-prepared and under-resourced — as they were later for going into Afghanistan’s Helmand province in 2006

Remember — these are not the views of laymen with no knowledge of military reality. One member, Professor Sir Lawrence Freedman, is a distinguished historian with long and close connections to the Army.

At the heart of the report is the finding that Iraq cannot properly be considered Blair’s war, of which the Armed Forces became victims — though 179 of its humbler members perished there.

It was, instead, a struggle that the senior soldiers, especially, were panting to wage. ‘They were gagging for it,’ in the words of one of those closely involved.

Admiral Lord Boyce, then Chief of Defence Staff, has recently sought to suggest that he was a sceptic. I am reliably told, however, that no document can be found, in which he records doubts about Britain’s commitment.

In one pre-war submission from the chiefs of staff to Downing Street — which now seems fantastic — they argue that if Britain’s Armed Forces take an active combat role in the invasion, the Americans will be sympathetic if they then accept only subsidiary responsibilities in the Iraq occupation.

At the heart of the report is the finding that Iraq cannot properly be considered Blair’s war, of which the Armed Forces became victims — though 179 of its humbler members perished there (pictured)

General Sir Michael Walker, head of the Army until just before the invasion and later Chief of Defence Staff, comes out of the story very badly. The Armed Forces allowed themselves to enthuse about a project for which they were woefully, shamefully ill-prepared and under-resourced — as they were later for going into Afghanistan’s Helmand province in 2006.

The lack of British planning for the occupation was criminally negligent. The only soldier to emerge with some credit is General Sir Mike Jackson, who succeeded Walker as Army chief and articulated frankly and before anybody else his conviction that the occupation was going horribly wrong.

The Armed Forces’ ‘can-do’ spirit, eagerness to earn their pay, to justify their existence or — as cynics would say — ‘play with their toys’, can be admirable. In recent times, however, it has produced some hideous embarrassments and disasters.

The best service that an Armed Forces chief can perform is to state honestly to the government what soldiers, sailors and airmen can and cannot deliver. This did not happen in 2002-3, and all the defence chiefs of the time share a heavy burden of blame.

The Army’s management of its operational share in the Iraq occupation, and especially its abdication of responsibility for Basra, seem shameful.

In the light of the current foreign policy crisis facing Britain in the Middle East, it is tempting to view Chilcot as a mere expensive exercise in archaeology.

That will certainly be the view of those who seek a public execution of Tony Blair, rather than his mere execration.

Critics will lambast the report’s sometimes elephantine circumlocutions, and the huge resources expended on producing it.

Yet I believe it establishes a record, a damning record, which should be critical not only to historians, but also to those who want Britain to be an effectively and honourably governed country.

Sir John Chilcot said yesterday, unveiling his report: ‘The main expectation I have is that it will not be possible in future to engage in a military or indeed a diplomatic endeavour on such a scale and of such gravity without really careful, challenging analysis and assessment, and collective political judgment applied to it.’

The best thing about Chilcot is not its findings, but the mountain of evidence it casts in stone

The events of 2011 — when the Etonian boy scout troop responsible for making foreign policy in Downing Street led our shambolic intervention in Libya to topple President Gaddafi — suggest that less has been learned from 2003 than we might hope.

At least over Libya and later Syria, the then Chief of Defence Staff General David Richards showed the courage to warn the Prime Minister, as Admiral Boyce did not warn Blair in 2003, that he was setting course for disaster.

As for those in Downing Street who were foolish enough to suppose that our participation in Bush’s Iraq tragedy would win us U.S. gratitude or even attention, we should realise that most Americans are scarcely aware of our presence on the set during their melodramas.

In the 603 pages of the most authoritative American account of the war, Bernard Trainor and Michael Gordon’s book Cobra II, Britain receives eight glancing mentions and Blair four.

It is not that the U.S. government dislikes us. It is that we rank extraordinarily small in its thinking. The most pathetic, awful thing about British participation in the Iraq war is that this country staked so much, and received in return absolutely nothing, not even a few breaks from Washington on other bilateral issues.

The best thing about Chilcot is not its findings, but the mountain of evidence it casts in stone.

This should form the basis for a primer for all those entering our government, either as politicians or state servants.

We shall again — perhaps often — find ourselves led by a Prime Minister who allows poor judgement, megalomania or moral fervour to lead him or her towards reckless courses.

The machinery of British governance exists to provide checks and balances to prevent such leaders from precipitating disasters.

It is not the duty, or even the right, of fellow-ministers, civil servants, intelligence chiefs, admirals and generals and law officers merely to allow themselves to become the obedient instruments of the government of the day — in this case, to become eager members of ‘Team Tony’.