Today London will see another landmark occasion. At Lancaster House, Tony Blair will bring together politicians from Northern Ireland, Scotland, Wales and the Irish Republic, as well as those from the Channel Islands and the Isle of Man, to launch the British Irish Council. And then, at Number 10, he and Bertie Ahern, together with David Trimble and Seamus Mallon, will launch the British Irish Inter-governmental Conference.
A new era in politics in the British Isles will have begun. The poison that the ideological battles of the 19th century introduced is being replaced by a series of practical, working relationships based on common sense and consent, which allow us to work together without infringing anyone's constitutional position.
In future when the British Irish Council meets, the discussion will be about how the different members can co-operate, drawing on their different experiences, to tackle issues such as drugs, the environment and social exclusion.
Similarly, when the British Irish Inter-governmental Conference meets the discussion will not be about the old conflict between our two countries over the constitutional position of Northern Ireland, but how to deepen and broaden that already unique relationship through greater bilateral co-operation. And, when Northern Ireland is discussed, its politicians will be at the table, not waiting outside to be told the outcome, as they have been for a generation.
That is the achievement of the Good Friday Agreement - a document which has allowed us to leave the past behind, and move forward to the new millennium with institutions which recognise the differences of who, and what, we are, rather than trying to impose any one particular identity.
We now have, not just an elected assembly in Northern Ireland, but an elected executive as well - self-government which, for the first time since Partition, truly represents all the people of Northern Ireland. Old enemies now sit around the same table, not because they agree about the constitutional future, but because they have accepted that it is better to work together to bring practical benefits to their people, rather than to perpetuate the conflict into a new century.
It has not been easy. Some unionists do find it difficult to accept Martin McGuinness as Education Minister, just as some republicans find it difficult to see Ian Paisley's Democratic Unionist Party in a government that they are committed to bringing down. But, for both, that is the price of seeing local people in charge of local affairs for the first time since 1974. And it is working. Both Martin McGuinness, and Peter Robinson, have, like their ministerial colleagues, committed themselves to working in the interests of both traditions for the benefit of Northern Ireland as a whole.
And the same is true of relations between Northern Ireland and the Republic. Since Partition this has been contested ground - the source of constant division, suspicion and, at worst, violence. A vicious circle in which any attempt to improve relations seemed to end up making them worse.
Those days are gone. The Good Friday Agreement finally resolved the fundamental issue. Any change to Northern Ireland's constitutional position can only come about with the consent of a majority of its people. Articles two and three of the Irish Constitution, which laid claim to Northern Ireland, are gone. In their place, a practical working relationship focused on the North/South Ministerial Council which met for the first time this week in Armagh. Ministers, from north and south of the border, around the same table discussing the issues that matter to their people.
The Good Friday Agreement is working. But, the transition to a new era must be complete. The Good Friday Agreement needs to be implemented in full. No longer must anyone live under the threat of violence. Those days, too, must be seen to be gone. That is why de-commissioning needs to happen as laid down in the Agreement, under the supervision of General John de Chastelain's International Commission. It is a voluntary act, but one that is an essential part of the Agreement, as all the parties have now accepted.
Leaving the past behind has been difficult for all sides in the past two years. For the families of victims the pain has been particularly acute, especially when they have seen those who killed or injured their loved ones leave prison early. Their pain puts a particular responsibility on all of us to make sure that the peace we create cannot easily be reversed.
In this context, de-commissioning is not the only issue still to be tackled. In the new year I will be announcing the outcome of the consultation process about the Patten Report on the future of policing in Northern Ireland. It is a subject which shows the feelings on all sides aroused by the events of the past 30 years, and I am fully aware of those sensitivities.
I intend to implement Patten's proposals but, I hope, in a way that carries the support and goodwill of both communities. Equally, I am aware of the balance we must keep between, on the one hand, scaling down the security forces' profile as quickly as possible to reflect the huge change there has been in Northern Ireland, while, on the other, not leaving people vulnerable to attack from dissidents, on both sides, who oppose progress.
That progress has been real. No longer does Northern Ireland look, and feel, like a battleground. Instead it looks like a society prepared for the new millennium - a society bursting with talent, the sort of talent that raised the standing stone on Strangford Lough. Educated, bright, enthusiastic and no longer living under the shadow of violence.
The writer is Secretary of State for Northern Ireland