There has never been a Labour Party conference like this one and there never will be again.
It should have been a celebration of Labour's emphatic General Election victory in June, which gave Tony Blair and his Government an unprecedented second term.
But the carnival is over and any warm post-election feeling has been overshadowed by New York's World Trade Centre turning to ashes.
Delegates will still gather in the Grand Hotel and mingle in the Metropole but instead of burning the candle at both ends, they are lighting it for peace and harmony.
The conference has not been cancelled, as some feared would happen, but it has been curtailed and international events will dominate the agenda as never before.
It has not been a good year for Britain or the Government. Foot-and-mouth developed into such a big problem, it caused the election to be postponed.
The upsetting pictures of animals being burned in great pyres were followed by the appalling images of the twin towers ablaze on September 11.
Tony Blair was last in Brighton on that awful day to talk to the TUC. On being told the news, he tore up his speech and returned to London, knowing the world would never be the same again.
There was a picture flashed around the globe of President George W Bush looking stricken as an aide told him the news while he was talking to children in a Florida school.
No one recorded what Mr Blair looked like when he heard what had happened but his reaction was quick and emphatic. Since then, he and the Government have been on a war footing.
The public mood changed abruptly, with consumer spending stopping and people feeling uneasy about enjoying themselves - the boom turned to gloom and doom.
At the TUC, Tony Blair had been expecting a rough ride over public-private partnerships but of course it never happened. The brothers and sisters went home early in the aftermath of terror.
Last week at Bournemouth, the Liberal Democrats became the only main party to stage a full conference but it was limp and lacklustre.
Now it is Labour's turn and somehow domestic issues seem tired and tawdry against the backdrop of thousands slaughtered in America and the probability of many more deaths to come in Afghanistan.
But there will be argument all the same as the party fissures between New and Old Labour.
The splits were a long time coming as even left-wingers who did not agree with the Blair revolution suspended their criticism as New Labour won power in 1997 after 18 years of Tory rule.
They could have been just as happy this year with almost the same election result but there was a feeling it happened not because Labour was loved, but because the Tories were still unelectable. The low turnout contributed to that feeling.
The Tories spent all summer involved in mutually destructive conflict before the emergence of Iain Duncan Smith as leader.
His transformation from outsider to insider proved for once in politics that fortune favours the bald but his appointment of people such as Bill Cash and Eric Forth indicates a move to the right, which might not please the public.
The Liberal Democrats, who gained seats in June, made much of their becoming the main party of opposition but leader Charles Kennedy was so laid back during the summer, he appeared to have fallen asleep.
Sensing their opportunity to become the unofficial opposition, Left-wingers of a kind not seen for a decade have broken their almost monastic vows of silence and have started making rumbles of discontent.
Labour is often described as a broad church and Tony Blair is frequently compared with a vicar but there are many dissident and troublesome sects emerging.
The Prime Minister will have to deal with them but will concentrate his mind on the more important question of dissident organisations elsewhere in the world who could cause more terror in the US and also in the UK.
He has been transformed by circumstances in the past three weeks from a peacetime Premier into a war leader but this first conflict of the 21st Century breaks all the normal rules.
Sixty years ago, Britain knew her enemy and concentrated her whole war effort against Germany and her allies. Now she is not even sure who the enemy is.
Brighton knows all about terrorism. It was there - 17 years ago - that the IRA bombed the Grand Hotel killing five people and injuring many more.
It is because of that outrage that all conferences of the governing party ever since, including this one, have met amid the most immense security possible in a democratic society.
Even after September 11, there was not much more to be done to the secure site where the conference and the main hotels are, except to make precautions more visible.
But being there in this armed fortress only adds to the sombre and warlike atmosphere of the conference. Tony Blair said life must go on but, at this conference, you know the terrorists feel death must go on too.
Even the weather is reflecting the grim picture. Originally, fine days were forecast but now there are storm clouds over Sussex. There will be no Indian summer and soon we will be plunged instead into an Afghan winter.
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