Let's use plain words: John Scarlett must go

Lord Butler and his colleagues have not delivered a whitewash. Much of their report is a thorough and balanced analysis of one of the greatest intelligence failures of modern times. Considering the likely tendency of all members of the Butler inquiry to give the intelligence services and their political masters the benefit of the doubt, surprisingly few of their findings are wilfully credulous - although some are.

Lord Butler and his colleagues have not delivered a whitewash. Much of their report is a thorough and balanced analysis of one of the greatest intelligence failures of modern times. Considering the likely tendency of all members of the Butler inquiry to give the intelligence services and their political masters the benefit of the doubt, surprisingly few of their findings are wilfully credulous - although some are.

The gross over-estimation of Saddam Hussein's biological and chemical weapons capability was not a one-off failure such as the failure to pre-empt the attack on America on 11 September 2001. Breaking a secret plot of that kind will always be immensely difficult. The belief that Iraq possessed weapons of mass destruction, on the other hand, was persistent and widespread - and was central to the British case for joining in the US invasion of Iraq. Now, four independent inquiries have cumulatively established that it was completely and utterly wrong. The Butler report, the last of the four, describes with some authority the who, how and why of that terrible error, even if the "who" is identified in collective terms.

Taken together, the picture painted by the Hutton and Butler inquiries is of the intelligence services, already deep in the grip of a global "groupthink", riven by turf wars that prevented experts from checking information from sources jealously guarded by rival services, desperately scrabbling for scraps of information to satisfy demands from the Prime Minister for evidence to substantiate his convictions.

Hutton revealed the email traffic, including the frantic appeal from John Scarlett, the chairman of the Joint Intelligence Committee, for "any items of intelligence that agencies think can and should be included" in the dossier. A dossier, Mr Scarlett told his agencies, that "No 10" wants to be "as strong as possible". Butler describes, in more muffled terms, how, in this atmosphere, the intelligence chiefs and the Prime Minister seized on information from "a new source on trial" who told them just what they wanted to hear - that Saddam was producing chemical and biological agents.

While much of the Butler report simply puts an official imprint on what we already know, its main revelation is that Tony Blair knew, or should have known, that this intelligence was unreliable. It was not referred to directly in the dossier, but it did "provide significant assurance" to its drafters. It should not have done, as MI6 effectively admitted when it "withdrew" the report in July last year. It would have done so much earlier if it had allowed the Defence Intelligence Staff, which emerges with some credit from Butler, to assess the intelligence.

Lord Butler's committee is measured in its language, but that makes its findings of failings at all levels, from the "validation" of sub-sources to the drafting of the Prime Minister's foreword to the dossier, all the more powerful. The claim that banned weapons were still being produced should not have been in the dossier. Nor should the "45 minutes".

Which brings us to the Butler report's perverse finding, which stands out all the more for the plainness of those around it. The report makes one exception to its policy of not naming names. It names John Scarlett as someone who should not step down. This makes no sense when read against the rest of the report. The heaviest weight of implied "collective" criticism is of MI6, which was responsible for most of the raw intelligence that was then cooked in Downing Street and its Cabinet Office adjunct. Sir Richard Dearlove, the director of MI6, retires at the end of this month. But Mr Scarlett should not succeed him, and it was wrong of the Prime Minister to approve his promotion before Butler delivered its verdict. The implication of the report, whatever Lord Butler's protestations, is that Mr Scarlett was an unsuitable person to chair the Joint Intelligence Committee - it should be chaired by someone "who is demonstrably beyond influence, and thus probably in his last post".

It would be in the interests of the credibility of the intelligence services - so vital to the security of the nation - if Mr Scarlett accepted this finding, and decided that chairman of the Joint Intelligence Committee was indeed his last post.