To me, Europe Day represents something unique in the history of our continent - an unprecedented period of peaceful co-operation between peoples previously so often at war among themselves.
I am 75 and the development of a common European purpose - and the UK's participation in it - has been the most important political issue of my lifetime. It was in particular the vision of Edward Heath (whom I had the privilege of meeting several times over a 30-year period) of Britain's rightful place in Europe that inspired me. Securing our membership of the then European Community in 1973 was, therefore, the most important political event of the last half century and Ted Heath was the only one who could have achieved it. (It was he who inspired me to join the European Movement, of which he became president, 50 years ago.)
But the significance of Europe Day is, for me, about even more than politics and economics. It is about being European. We British are as truly European as any other people in our continent. We enjoy the same matchless pan-European cultural heritage, accumulated over millennia, in music, the visual arts, literature and architecture: all the things that enrich our lives.
My wife and I were in Germany on referendum day and afterwards (having spent months campaigning for Remain): we felt as if we were leaving the family. And the Germans around us were as sad as we were. Brexit is a terrible mistake. Worse, it is an abomination. It must be stopped.