AP Photo

When the last French socialist president, Francois Mitterrand, was preparing for victory, it was my job as a diplomat to accompany him on a trip to London to call on Jim Callaghan. En route from the airport to No 10, I arranged for him to drop in to Kew Gardens. A mistake. He was so enthralled I couldn't get him out, and we turned up a trifle late for the prime minister.

The point of the story is French insularity. Mitterrand was a passionate arboriculturalist, yet he knew nothing of the glories of Kew. In France, insularity can go along with a romantic nationalism, on Left and Right, and with Francois Hollande's victory we are seeing more of that today.

A policy of national conceit was how my ambassador in Paris, Sir Nicholas Henderson, characterised French attitudes in...