They may not be the best of friends, but Blair and Chirac need each other

Chirac knows that an influential Europe cannot exist without Britain and its special connection to the US

Tom-and-Jerry politics rules. Jacques is coming to London to see Tony. It is therefore evident that Jacques plans to bash Tony and Tony plans to bash Jacques. In a briefing for British correspondents at the Elysée palace the other night - the first presidential briefing given to the British press in Paris for more than a decade - Jacques Chirac spent the best part of 50 minutes saying how much he esteemed Tony Blair (and his young son Leo); how he and Mr Blair planned to work together, despite their differences, on the Middle East and the EU.

Tom-and-Jerry politics rules. Jacques is coming to London to see Tony. It is therefore evident that Jacques plans to bash Tony and Tony plans to bash Jacques. In a briefing for British correspondents at the Elysée palace the other night - the first presidential briefing given to the British press in Paris for more than a decade - Jacques Chirac spent the best part of 50 minutes saying how much he esteemed Tony Blair (and his young son Leo); how he and Mr Blair planned to work together, despite their differences, on the Middle East and the EU.

He described, rather fetchingly, the relationship between Britain and France, and implicitly between Blair and himself, as one of " amour violent" - of tough love or a tempestuous love affair. He also said - what seemed fairly obvious - that the United States, under its present leaders, did not feel in any way bound to return favours: to "send back the elevator", as the French say, not even to the faithful British. His tone was one of regret, almost foreboding, rather than pleasure.

On the same night, Tony Blair made a speech in which he said that he believed that Europe - and implicitly mostly Britain - could help to shape US foreign policy for the better, despite his apparent rebuff from Washington on a Middle East peace conference; and despite the eclipse of Colin Powell. The fact that the two comments were made (coincidentally) on the same night was interpreted by some headlines in Britain as an "open clash" between Chirac and Blair or a direct and deliberate "attack" by the French president on the British prime minister. In other words, more a question of "violence" than "amour".

Chirac and Blair clearly have "divergent views", as diplomats say, on these questions and on many others. OK, then they disagree. Does that make every comment by M. Chirac, in defence of his own point of view, a "clash" or an "attack"? Does that make M. Chirac's two-day visit to London, starting today, an inevitable Tom and Jerry, show in which any semiquaver of disagreement between the men is orchestrated in the press as a "snub" or "confrontation"? That will, inevitably, be the tone of much of what you will read or hear over the next couple of days. We lived in knee-jerk world, but much of this knee-jerkery will miss the point.

It is only 20 months since the British government accused the French - openly - of playing a selfish, devious game in its opposition to the US-led invasion of Iraq. The French government - less openly - accused the British of foolishly signing up for an obsessive, ideologically-driven US crusade on doubtful evidence of an immediate Iraqi threat. (Both were partly right and both were partly wrong.)

At one point, the French protested officially (and accurately, as Sir Stephen Wall, former Blair foreign policy chief, has now admitted) that the British government lied to press and Parliament about President Chirac's position in order to stir up anti-French feeling and war fever. Franco-British government-to-government relations were at their lowest ebb for 40 years, since President De Gaulle vetoed British membership of the EEC.

Twenty months on, what do we see? Relations between the French and American governments are deep-frozen, and likely to remain so while presidents Bush and Chirac remain in power. Relations between the French and British governments have returned to a remarkable level of calm, even outward warmth. Tony Blair has been admitted to some of the Paris-Berlin cabals that traditionally precede all big EU occasions. The Franco-German axis may yet become a Franco-German-British three-wheeler.

Mr Blair has pushed ahead with the Franco-British-led plans for an EU defence policy, semi-detached from Nato. Detailed plans are being negotiated for Franco-British co-operation in the construction of a new generation of aircraft carriers (two British and one French). The Rumsfeldian - and maybe briefly Blairist - fantasy of a "New Europe" controlled from a Polish-Spanish-British periphery have collapsed.

Although still divided by some old favourites, such as farming and budget rebates and taxation policy, Britain and France take a broadly similar view of how the EU should develop. In negotiations on the new European constitution, there were surprisingly few fundamentals on which France and Britain disagreed. (So much so that the constitution is now seen by the British right as a statist French conspiracy and by the French left as a Thatcherist Anglo-Saxon plot.)

On one level, the new Chirac-Blair cosiness can be dismissed as the inevitable, cynical, surface accommodation of governments and countries that are doomed by geography and history to associate with one another. Polite Franco-American relations are, in a sense, optional. Polite Franco-British relations are not.

The celebration of the centenary of the Entente Cordiale this year obliged the two governments to put on a happy face. Beyond that, President Chirac needs Tony Blair as a connection to Washington; Tony Blair needs a repaired relationship with Chirac to prove that he is still a Great European.

All of this is true, but it is not the whole truth. Chirac and Blair may not be friends; they may not agree on everything; but, stripped of the domestically-shaped rhetoric, their objectives and ideas converge. Chirac's vision of a "multi-polar" world is usually presented in Britain as a challenge to US supremacy. It is seen in France as a refusal to accept that America must always be right, just because America is America, no matter how dubious the views of those in power.

Blair believes that Europe (by which he usually means Britain) can draw the US towards a more collegial attitude to foreign affairs, the world economy, the environment. Chirac believes that only a strong and united Europe (by which he usually means one that agrees with France) can hope to do that.

Chirac knows that an influential Europe cannot exist without Britain and its special connection with the US; Blair knows that his influence in America (if any) is partly personal and partly historic. But it also depends (given America's permanent, not just Bushian, self-absorption) on Britain's having another, European, card to play. Hence, Mr Blair's on-off and now "on again" love affair with European defence and security policy, which is inevitably - given relative military spending - mostly a Franco-British game.

There are some practical, military and commercial arguments for an EU defence policy but there are also unspoken missions. They are not to destroy Nato. They are to create a core of unity within the new, looser, sprawling EU (a core of unity to which, unlike the euro, Britain can happily belong). They are also to remind Washington that Britain has other friends and that Europe may not always remain a quarrelsome raft, drifting on a stormy ocean.

Read the entertaining headlines on "rifts" and "clashes" this week. Read also the small-print of Blair-Chirac rapprochement on EU defence, on global warming, on third world, especially African, trade and debt. Even Tom and Jerry agree sometimes.