When Winston Churchill coined the phrase 'special relationship' to describe the bond between Britain and America in 1946, he was perhaps romanticising a little. America had turned the tide of both World Wars at a time when Britain was desperately struggling, but on both occasions her decision to intervene was a pragmatic one, catalysed by an attack on US shipping, rather than an altruistic sense of duty to the old motherland.

But, at the time, Churchill's words reflected the zeitgeist. Britain and America, the world's two great English-speaking democracies, were united in suspicion of the monolithic Communist empire to the east, and those irascible Germans whose aggression had sparked the two global conflicts. Both London and Washington were preoccupied with preventing a fresh eruption of violence in mainland Europe. There was no need for a formal agreement to bind their respective foreign policies together.

The two countries shared clear economic ties, too. Traditional industries continued to flourish on both sides of the pond, nourishing decades-old trading synergies. The raw materials churned out by Britain's empire fed the US leviathan, and the industrial hubs of Manchester, Liverpool and Glasgow relied heavily on shipments from across the Atlantic. With much of the rest of the world under Communist control, or crippled by the effects of the war, American business, as well as its financial aid, was crucial to Britain's post-war economic recovery.

Now, almost 70 years on from the end of World War Two, the world looks a very different place. The double-headed monster of Communism and Nazism, which once united Britain and America in fear, is long dead. Germany and Japan have emerged from the rubble of 1945 to become economic titans in their own right, while a profusion of new democracies have replaced shadowy suspicion with optimism and opportunity.

In Britain and America, the changes have been equally seismic, sweeping away the old Anglo-Saxon elites which bound the two countries in blood and custom. An estimated 37 million Americans now speak Spanish as a first language, while Britain has become the most ethnically diverse country in Europe, its multi-racial, multi-lingual cities bearing no relation to the grey, crumbling smogscapes of Churchill's age.

Economically, the US and the UK are unrecognisable. Britain's heavy industries were flattened in the 1980s, while those in America are flatlining - if you want evidence, just look at Detroit's recent application for bankruptcy. Both countries have sought to rebuild their economies around modern industries, such as technology and financial services, while seeking out new trading opportunities in burgeoning nations such as India, China and Brazil.

All this has meant that Britain's old reliance on America has lessened considerably. The US has been supplanted by Germany as Britain's biggest export market, and is down to fourth on its list of import partners. UK Trade and Investment recently released a list of 19 'priority' markets for exporters to target, and America did not even make the list - a sure sign that Britain's economic boffins believe the country's future lies in new markets, away from the tried-and-trusted trans-atlantic tie-ups.

And what about the military bond which was, of course, central to Anglo-American relations in the middle of the twentieth century? Well one could argue that, here, the divergence has been even more marked. While America continues to pursue a belligerent, expansionist foreign policy, Britain has cast off its old jingoistic arrogance; only once since 1945 has it gone to war unilaterally, in 1982 over a group of islands off the coast of Argentina. In each of its other post-WWII conflicts - Iraq, Afghanistan, Kosovo - Britain has gone in behind America, to a background of hostility at home.

Now President Obama is once again seeking British support as he scrambles towards a war in Syria. A poll conducted earlier this week revealed three-quarters of the UK population oppose Obama's stance, while, just as telling, two-thirds of the British population wouldn't care if the US-UK relationship was fractured. The public simply no longer wish to be manacled to America's bullish foreign policy.

And why should they? This is a country, which, since the Second World War, has prosecuted disastrous wars in Vietnam and Iraq, backed atrocious dictatorships in several Latin American countries and ferried aid to the Mujahadeen, a decision which sowed the seeds of 9/11. After so many blunders, British people are tired of their country tagging along on America's foreign adventures, and see no cultural, economic or political obligation to do so.

None of this is to suggest that Britain should categorically rule itself out of war in Syria. If Cameron and his fellow ministers decide that the chance to snuff out the threat of Assad, and his war crimes, is worth the price of British lives, they should intervene. But they should not be guided by Washington; the special bond between Britain and America has long been broken, and British soldiers should not be placed in danger for the sake of this anachronistic union.