Tony Blair's Pyrrhic election victory may well have changed the fundamental principle of British foreign policy for more than 60 years. For the first time since 1941, it may no longer be the automatic choice to stick close to Washington.
Even in the Suez crisis of 1956, when the United States forced Sir Anthony Eden's government to stop in mid-attack against Col Nasser's Egypt, it was Eden himself rather than the US who got the blame in Britain. Relations with Washington were soon better than ever.
Tony Blair won an historic third election victory, but at what price?
They survived Harold Wilson's point-blank refusal to send British troops to Vietnam, in spite of all President Lyndon Johnson's threats and pleading.
But the fall-out from Mr Blair's willingness to join in the invasion of Iraq has changed everything. From now on, it will be a very bold or very foolhardy prime minister who will forget what happened as a result.
The relationship with Washington will still be of huge importance; but if it comes to a decision whether to side with the United States or with the majority inside the European Union, as it did in 2003, Europe rather than America may well be the default option.
It was, of course, Iraq which, more than anything else, changed Mr Blair's fortunes for the worse. He came to power in 1997 promising a more open and natural style of politics. Most people saw him as relaxed, honest and decent.
And he was young. In 2000, he and his wife were the first couple in 10 Downing Street for a century and a half to have a baby.
Image and spin
After the John Major years he seemed like a real breath of fresh air - as clever as Bill Clinton and Jacques Chirac, but without the accompanying whiff of scandal, and livelier and brighter than George W Bush.
True, it soon became clear that image-making and spin-doctoring were the life-blood of his government, but most people accepted that. Then came the obfuscation and misinformation about Saddam Hussein's Iraq.
Now his reputation for frankness and honesty has gone. His followers found, as they knocked on the voters' doors during the election campaign, that they would have a better reception if they didn't mention his name. Iraq wasn't the only election issue, but it was the defining one.
Now, with Iraq's civil war worsening month by month, Mr Blair has paid a ferocious price for his decision to stand shoulder to shoulder with Mr Bush. He may linger on in power for a year or more, but his majority in Parliament has been badly cut, and the magic has evaporated.
The legacy of the Suez Canal crisis lives on half a century later
Just as no British prime minister for half a century has forgotten Suez, so none of Mr Blair's successors for the next half-century will entirely forget what happened to Tony Blair when he chose to support an American president in preference to most of the rest of Europe.
But can we really expect that anything like the same situation will arise again? The invasion of Iraq has been, in Kipling's words, "no end of a lesson" to American politicians as well.
Washington's strategy seems to be to get American troops off the streets in Iraq within a year, first of all to the huge barracks that have been built far from any centres of population, and then out of the country for good.
After that, the Iraqi government will be left to sink or swim on its own: a process which we once knew as 'Vietnamization'.
In these circumstances, it is hard to think that President Bush will get involved in another shooting war in the Middle East.
General Richard Myers, the chairman of the US joint chiefs of staff, says the American commitments in Iraq and Afghanistan could limit the ability of the US to fight another war - a diplomatic way of saying: "Don't even think about it."
We can forget about ground wars against Iran or Syria, or anywhere else - unless, as with the first Gulf War, the case for action becomes so strong that most of the world's other big countries will want to get involved.
So neither Mr Blair nor his successor, it seems reasonable to suppose, will have to face another choice like the one in 2003: to side with Washington or with the European majority.
But if such a thing were to happen, they or future British prime ministers will look back on the events of 2003-5 and shudder at the thought of backing America against most of Europe and against public opinion at home.
The basic affection for America will remain, and will be stronger in Britain than it will in most other European countries.
But, chastened by what has happened this time, future British governments will be much more careful than Mr Blair about taking action for a cause that doesn't have full and clear international backing.
Read John Simpson's previous columns:
Despite disagreeing with the decision to go to war, John Simpson's glib comparison with Suez is utterly misleading. Anthony Eden was forced to resign in disgrace after a humiliating run on Sterling precipitated by the rejection of the invasion by the US. Damaged as he is, Blair has clung on to power, Britain has not been embarrassed on the international stage in the same manner and the troops are yet to pull out. The faux historical nonsense that has been talked about Iraq (it's like Suez/Vietnam/etc. all over again!) is frankly absurd.
Alex, Cambridge, UK
John Simpson's comments are reasonable. The greater issue for our very future that we face is how long do we avoid developing alternate technologies thus alleviating the importance in particular the USA for oil in the Middle East? It would appear until we have liberal administrations in the USA and the UK can we really solve the problem.
Christopher Wheatley, London
A political merger with Europe against the US would push Britain into a European super-state, which would cause its own problems. I think if Blair had not gone to war in Iraq he may have had a worse election. The Tories would have accused him of destroying the special relationship and forcing us to merge with Europe.
Colin Allott, Hull, England
I agree that a war with Syria and Iran now looks unlikely given the mess in Iraq. But because of the war in Iraq, and the US role in the Arab-Israeli conflict, the whole region is very unstable now. What if there is serious unrest in Saudi Arabia with 1/4 of the world's cheap oil reserves? What does the US/UK, the world do then?
Geoff Payne, London, England
What is this "European majority" he is writing about? Spain (at the time), Portugal, Italy and many central and eastern European states chose to support Washington's position against Saddam, and many of these contributed troops in Iraq. It is only in the light of events after the initial battlefield victory that the paucity of WMD evidence and reconstruction planning has shown the folly of following along with the US "leadership" in Iraq. I don't believe Blair had much choice but to stay the course and influence US policy as far as he possibly could. Bush really owes him on this.
I disagree on one point; that the Americans will eventually leave Iraq for good. It is widely suspected that the US wants a permanent military base in the region. Geographically and politically the centre of Iraq is an ideal location from where to be able to menace Syria and Iran, protect the oil fields and keep a puppet Iraqi democracy in check.
A 60 seat victory after two terms and an unpopular war will be seen by history as ... an incredible victory for a popular leader.
John Simpson usually writes a sensible line based on understanding. Sadly, in this column, he regurgitates the same nonsense as all the other columnists, who dislike the fact that there are no conceivable options to Labour at the moment, and allow that discomfort to sway them to insufficiently considered musings.
Read Churchill's "History of the English speaking peoples" to be reminded to whom go the spoils!
J Germain, Montreal, Canada