"Britain finds its role". What a headline that would be. Dean Acheson's famous jibe that "Great Britain has lost an empire and not yet found a role" is as apt today as it was when he made it in 1962. Those to the left say "choose Europe", those to the right say "choose America", those behind say "remain a right little, tight little England", and those in front have no one to support them. Yet the role for Britain is staring us in the face. Or rather, in the four faces of Janus Britain: Island and World, Europe and America.

Historically, Britain is a child of Europe and a parent of America. Those ties were attenuated, but never broken, by the experience of Island-Empire. Economically, politically, culturally, militarily, intellectually, socially we are now inextricably intertwined with both Europe and America. To choose one or the other would require a major amputation.

So the role that stares us in the face is to be the leading advocate and practitioner of the most intensive cooperation between Europe and America. To be friend and interpreter in both directions. To take the spirit of a 20th-century west, created, in no small part, by Winston Churchill, and carry it forward into the 21st-century post-west: a west that goes far beyond the boundaries of the historic west, and therefore, in an important sense, ceases to be the west, as it works towards a free world.

Tony Blair has grasped and articulated this British national interest, role and chance better than any of his predecessors. But his central image of Britain as "the bridge" is not a good one. The bridge we need is one between the whole of Europe and America. It should be the biggest bridge in the world: 3,000 miles long and as many lanes wide.

In the new, enlarged European Union, Britain, like America, faces a choice. We can cultivate alliances of the willing as during the Iraq war, or we can seek to win the whole of Europe to what seems to us the right course. The latter approach is more difficult, but offers a much bigger pay-off at the end.

What we need is nothing less than a historic compromise with our ancient enemy, France. Britain alone is too small and weak to be a major partner for the US, especially since American leaders generally feel they can take the British for granted. If even Churchill, with the whole might of the British empire behind him, found himself compelled to "beg, like Fala" (Roosevelt's dog), how much more must that be true of a medium-sized European state in relation to the world's only hyperpower.

Blair discovered this over Iraq. Speaking to Washington on behalf of 60 million British is one thing; speaking on behalf of 460 million Europeans would be quite another. By contrast, trying to rally 460 million Europeans around a neo-Gaullist alternative "pole" to the US is a hopeless cause.

Half of them won't follow; the US hyperpower will ignore Paris and go it alone, or divide and rule in Europe. Trying to gather Europeans around a common position as a Euroatlanticist partner of the US is the best course for both Britain and France.

Crucial to this new understanding will be the voice of Germany. In its own enlightened self-interest, Germany should play the role of "honest broker" between France and Britain. This alone will allow it to continue its own balancing act between Paris and Washington, which has served the Federal Republic so well. America, too, should support this reconciliation in its own enlightened self-interest. It will not be easy and it will take time, but history is full of surprises.

Britain also needs an internal historic compromise to complement, and in fact permit, the external one with France. The essence of this is simple: the British right must accept Europe and the British left must accept America.

This doesn't mean to accept every stupid directive that comes out of Brussels or every stupid policy that comes out of Washington. It means accepting the reality of Janus Britain: that our future depends on attempting to influence the policies of Europe and America so they are compatible with each other and with our own needs.

Such a strategic foreign policy consensus would have to be sustained by a more developed popular sense of where Britain is and who we have become - 60 years after D-day. At the moment, because of the way history is taught in British schools, few children can locate themselves in any national story. How about every schoolchild learning the story of Britain in terms of the interaction between those four faces, Island and World, Europe and America?

And how many people in Britain grasp the relationship between the US Congress, supreme court and president? How many know the difference between the president of the European commission and the presidency of the Council of Ministers? A world island needs a "civics" to match. Most British school-leavers don't even possess the basic facts.

Then there's information for adults. The BBC does a fine job, but the term "newspaper" is by now a complete misnomer for many of our papers.

We need a revolt of the politicians, who should finally summon the courage to face down the media barons. But we also need a revolt of the journalists. After all, journalists, not proprietors, actually write and edit these papers.

A Britain thus politically focused, educated and informed would have notable strengths. Being so intimate with Europe and America means we have the chance to take the best of both.

· This is the second of five edited extracts from Free World: Why a Crisis of the West Reveals the Opportunity of Our Time by Timothy Garton Ash, to be published on July 1 by Penguin, £17.99.

timothy.garton.ash@theguardian.com