Trouble at the top: Blair and Brown are feuding, while Cook is scheming

Relations between the two men have never been worse. One observer told me that these days they grate on each other

A couple of days ago, a Eurostar train was stuck for five hours in darkness and ignorance; no one was able to tell the passengers what was happening. What an apt metaphor for British politics.

The immediate political future has never seemed more uncertain; the political structures have never rested on such a fragile basis of popular approval. Our present party system is only held together by the constraints of the British electoral process. Under proportional representation, it would have disintegrated long ago.

The fault-lines are most apparent in the Labour Party, which makes Mr Blair's achievement the more remarkable. He has not only remained in government with a divided party; he has stayed comfortable in the opinion polls. This may not last, however, for the splits are worse than ever – not to mention the forthcoming war.

Personality disputes can exacerbate policy problems. On the public services and on Europe, Tony Blair and Gordon Brown have different instincts. On public services, Mr Blair would be happy to expand the role of market forces. Mr Brown is warier, believing in a continuing role for government, partly as a trustee for egalitarianism.

On Europe, it is Mr Brown who is cautious. The PM wants Britain to be fully involved in the building of Europe and tends to be dismissive of short-term economic anxieties. As far as he is concerned, the five economic tests for membership of the euro were never that important. They were drafted to mean whatever the Government wanted them to mean and to add weight to a "yes'' campaign in a referendum. They were never intended to be an obstacle to holding that referendum.

The Chancellor sees things differently. He regards himself as the custodian of the economy and is unwilling to jeopardise what he still believes to be his economic achievements. He takes the tests seriously.

So there are differences, but these are great and complex questions on which intelligent men are bound to have divergent attitudes. Given goodwill, this need not preclude ultimate convergence on agreed positions. Now, however, there is the opposite of goodwill. Relations between the two men have never been worse. One well-placed observer told me that these days, they grate on one another. There used to be a sufficient residue of affection and respect to float the ship off the rocks of the day's disagreements: no longer. Given all this, it is hard to see how the Government can have a strategy.

A breakdown of the Blair-Brown partnership inflames other personality disputes while adding to policy problems. Back in 1995, when John Redwood stood against John Major, he was not only destabilising the Major government. He wanted to destabilise Michael Portillo, by encouraging Tory MPs to reject the widespread assumption that Mr Portillo would automatically become the party's next leader. Today, Robin Cook is engaged in a similar exercise, against Gordon Brown as well as Tony Blair. Mr Brown sees himself as a frustrated crown prince; Mr Cook has other ideas.

The pot boils more vigorously because of the long-standing antagonism between Messrs Brown and Cook, who fell out about 30 years ago over something to do with Scottish politics, though no one else can remember precisely what. As a result of this antique and trivial quarrel, the two barely grunt at one another. Mr Brown is especially good at nursing his wrath to keep it warm, and Mr Cook knows that Premier Brown's first act would be to sack Robin Cook. So he is determined to put himself in a position to mount a leadership challenge, even if this means being sacked by Premier Blair – which could work to his advantage. This might be the time for aspirant Labour leaders to distance themselves from the Blair Cabinet.

Leadership speculation is not going to die down and is bound to undermine the Government's authority, making it even less likely that there could be a successful euro referendum, especially as other European issues are about to intrude. When Valéry Giscard d'Estaing was put in charge of the EU's constitutional convention, it was assumed in Whitehall that this would merely be another exercise in higher European rhetorical grandiosity, and that Giscard would be so delighted to have a great role with which to massage his vanity that he would draw out its proceedings indefinitely. That was a crucial misreading. Giscard may be vain, but he wants a memorial more enduring than endless committee meetings. He is seeking his place in history as Europe's Jefferson and Madison; the progenitor of Europe's federalist papers.

This is a serious embarrassment to Mr Blair. Peter Hain has been instructed to bluster about the unacceptability of certain passages in the Giscard report, but it will not be easy for the UK to secure anything except cosmetic changes. There is no compulsion for Britain to sign up to Giscard, but failure to do so would remove us from Europe's inner core, thus destroying Mr Blair's European diplomacy.

Up to now, No 10 has been hoping that no one would notice the Giscard report and that it could use its parliamentary majority to smuggle the document into law. But once there was a finished text, it was never likely to be ignored. No 10 is now terrified lest the popular eurosceptic press should demand a referendum on the Giscard proposals. That is going to happen.

Over the past few days, Mr Blair's spinners have informed us that he is in a new, resolute mood, determined to do what is right no matter what the focus groups say – and not only over Iraq. On the public services, too, we will witness his rebirth as a conviction politician. All this remains to be seen, but on European matters, Mr Blair appears as reluctant as ever to confront a hostile public opinion. Yet Giscard may give him no alternative.

Nor will George Bush. War is imminent. The Saudis and others are desperate to persuade Saddam to leave Iraq, but it seems unlikely that he will reconcile himself to spending the rest of his days under Saudi supervision in the Idi Amin guesthouse for redundant mass murderers.

Mr Blair is still hoping that the Saudis succeed, with the UN as a fallback position. He will tell us that he and President Bush would like a new resolution to enhance their international legitimacy, but most of his thoughts are on his legitimacy within the Labour Party. As America is determined to act anyway, there will probably be a new UN resolution; most Security Council members will see no point in giving gratuitous offence to the US. But the best that Mr Blair can hope for is a resolution in general terms; it is hardly likely to urge the allies on to war.

War even under a vague resolution would cause widespread Labour dismay. War without a resolution could break Mr Blair's hold on his party. At the end of July, as I informed Independent readers, the Labour whips were talking about 50 rebels, mainly drawn from the usual suspects plus a couple of marginal ministers. That now seems like a serious underestimate.