Tony Blair's credibility takes yet another hit

The Prime Minister is like an experienced mountaineer who begins to wonder if this time he won't return

Let us recall the method for decoding the Prime Minister's statements. The key is that his positive, unambiguous assertions, often emphatically expressed, are not primarily concerned with the truth but with what he believes ought to be the case. When Tony Blair told reporters travelling with him in Asia that he had had nothing to do with the naming of Dr Kelly, that meant "as Prime Minister, I should have had nothing to with the the outing of the government scientist". The Hutton inquiry has demonstrated that Mr Blair was intimately involved in the decision.

Now apply this approach to one of the Prime Minister's much quoted phrases in the speech he gave to the Labour Party conference last week: "After six years, more battered without but stronger within". Translation: "After six years, I should be stronger within".

Fact one: not strong enough to turn up to the annual meeting of the United Nations in New York two weeks ago even though George Bush, Jacques Chirac and Gerhard Schröder were present.

Fact two: Mr Blair would not take the press briefing in Rome on Saturday at the end of the European summit meeting. Jack Straw substituted for him. A British official said the Prime Minister could think of "better things" to do.

My guess is that Mr Blair actually feels weaker within. He is still courageous; he does most of what he has to do and often very well. But he also beginning to feel more scared than he used to be.

He is like a very experienced mountaineer who finds the climb he is doing more worrying than usual and wonders whether this time he won't return. And that feeling, if I am right, will have been exacerbated by reading the extracts from Robin Cook's diaries which were published yesterday.

On 5 March this year, just two weeks before the invasion of Iraq, Mr Cook saw the Prime Minister. He argued that if Hans Blix needed more time to complete his arms inspection task in Iraq, he should be given it. We should be prepared to give him until autumn.

Mr. Blair replied: "I don't know if I could do that. Left to himself, Bush would have gone to war in January. No, not in January, but back in September."

In other words, the natural public expectation that the Prime Minister would carefully weigh Mr Blix's findings is shown to have been unrealistic. Mr Blair was playing a part in a charade directed by the American President.

More seriously, Mr Cook referred the Prime Minister to the briefing he had received from John Scarlett, the head of the Joint Intelligence Committee. Mr Cook asked: "It's clear from the private briefing I have had that Saddam has no weapons of mass destruction in a sense of weapons that could strike at strategic cities. But he probably does have several thousand battlefield chemical munitions. Do you never worry that he might use them against British troops?" To which Mr Blair replied: "Yes, but all the effort he has had to put into concealment makes it difficult for him to assemble them quickly for use."

As Mr Cook notes, what was striking about this exchange, as it had been when he met Mr Scarlett, was that neither the head of the Joint Intelligence Committee nor the Prime Minister had tried to argue him out of his conclusion that Saddam did not have real weapons of mass destruction.

But it is Mr Cook's third point which will make the experienced mountaineer feel more nervous still. It is this. The rules of the House of Commons require ministers to correct the record as soon as they are aware that they may have misled Parliament.

So the question is whether the Prime Minister learnt that some of the claims presented to Parliament in the September dossier were false and if he did, when he did. The evidence that Mr Blair did come to realise that errors had been made before Iraq was invaded is circumstantial but powerful.

The contentious assertions in the dossier were gradually dropped. No mention was made of the 45-minute claim in the Prime Minister's speech in the war debate on 18 March. The US Secretary of State, Colin Powell, decided to use neither the Niger uranium claim in his speech to the Security Council in March nor the 45-minute assertion. Mr Cook says: "Given the intimate relationship between State Department and Foreign Office it is implausible that his (Mr Powell's) cautious scepticism did not become known in London."

Suppose that Mr Cook turns his third point into a question to the Prime Minister when Parliament reassembles. Mr Cook: "When did the Prime Minister become aware that some of the claims made in the September dossier were mistaken?" Now I apply my system of decoding Prime Ministerial statements to supply Mr Blair's likely reply. Prime Minister: "No credible evidence that any of the claims in the September dossier were erroneous came to my attention. I can emphatically assure members that any ministerial statements which inadvertently mislead the house are always corrected as soon as possible."

Nonetheless, step by step, Mr Blair becomes more exposed. The reason is that a great crime always has consequences. More than ever I believe that Iraq will eventually bring down both Mr Blair and Mr Bush, the former as a result of a parliamentary process, the latter at the next presidential election.