As it happens, this was one of the rather rare moments in the chequered history of our relations with the EU when I was not physically present.
But I was very much there in spirit, having worked with Sir Pierson Dixon, the leader of the official delegation under Ted Heath in the first Brussels negotiations, and bitterly resented de Gaulle's veto in 1963.
During the 1960s I had become wholly convinced that British membership of the EC was essential for Britain and important for Europe.
So the signature of the Accession Treaty was a wonderful moment for me, followed within a couple of months by a call from the Foreign Office to tell me to return from Washington and become head of the (then only) European Integration Department in the Foreign Office. Since then the EU has been part of my life - Under-Secretary in charge of "re-negotiation of the terms of entry" under Jim Callaghan as Foreign Secretary; Deputy-Secretary in charge of Europe and Economic Affairs when the European Monetary System was created in 1978-79; Permanent Representative in Brussels under Margaret Thatcher (1979-85), when we solved the British budget problem after five years' negotiation and launched the campaign for the Single Market; Chairman of the City's European Committee (1988-93) and originator of the British government's "hard-ecu" plan in 1990; and now, finally, Labour's Special Envoy on Enlargement.
We have had our successful moments - the two-to-one vote in the 1975 referendum, the huge and permanent refund of our excessive net contribution to the EU budget agreed at Fontainebleau in 1984, and above all, the launching of the Single Market at Margaret Thatcher's initiative with the Treaty amendments agreed at Luxembourg in 1985 in the Single European Act.
But alas, ever since John Major declared in 1992 - no doubt he meant it - that Britain's place must be at the heart of Europe, we have been sliding steadily on to the periphery.
Here we find ourselves in 1997, after 25 years of membership, with less understanding of the issues than we had 20 years ago.
The people of this country have been told by the so-called Euro-sceptics for the last five years that Germany and France are about to create a "federation", a government of the United States of Europe, which will result in Britain being abolished. A majority of them seem to believe this nonsense. I can assure readers that there are no Frenchmen who want to abolish France!
The Maastricht treaty of 1992 is responsible for much of this. It is incomprehensible. It lays down a very high-risk and rushed route to Monetary Union - a route, incidentally, which it may yet prove impractical for the EU to follow.
Though I may be being a little unfair, I blame John Major to some extent even for Maastricht. If he had not been so intent on securing opt-outs from EMU and the Social Chapters he could have deployed his persuasive and negotiating skills to improving the substance.
Things have now got even worse. Having negligently allowed the BSE crisis to happen, the Cabinet, terrified by the Euro-sceptics, tried "non-cooperation" ie, vetoing things we were in favour of.
Not surprisingly, this did not work. We have also taken an ideological and negative line in the IGC designed to prepare for enlargement.
The consequence of thus appeasing our ill-informed Euro-sceptics has thus been to reduce our influence to the lowest point ever. It is time for a fresh start.