Miles Kington: The French count who seemed to live for centuries

There are, in my experience, three stages in staving off boredom in a train journey. The first stage is staring out of the window. The second stage is studying one's travelling companions. The third stage is studying what they are reading.

So it was that, last Wednesday, I began my Eurostar trip from Waterloo to Paris by intently scrutinising the English landscape. Before we got to Clapham this had palled, and I transferred my attention to the other three people at the same table as me. Two were men. One of them was called Andrew and the other was called Nick. (There was no magic or telepathy involved in this. I already knew them quite well. They had even paid for my ticket, and were taking me to Paris to make me do a radio interview with Antoine de Caunes.)

There being no percentage in staring at familiar people, I turned my attention to the fourth person at the table. She was a chic, attractive Frenchwoman whom, when younger, I would have tried to lure into conversation, especially if Andrew and Nick had not been there, but who showed no signs of interest in anything outside her book. The book was a new French hardback. It showed a portrait of an 18th-century man in a wig and was called Saint German; l'homme qui ne voulait pas mourir, or Saint German, The Man Who Did Not Wish To Die.

I had never heard of Saint Germain, and did not know why he did not wish to die, any more than the rest of us do not want to die, so when I got back home (after a fascinating encounter with Antoine de Caunes, though I cannot tell you what he said, as Andrew and Nick have got it all on their recording machines) I went on the internet and found out that the Count of Saint Germain was a most extraordinary person, so extraordinary that I cannot understand why I have not heard of him before.

He bobs in and out of French society all through the 1700s, yet everyone agrees that he never looked more than about 40, however old he got, and the rumour soon spread that he had the elixir of youth. He became the intimate companion of Louis XV and spent many evenings along with him and Madame de Pompadour, entertaining them with tales of his travels and the famous people he had known. He spoke many languages, and played the violin immaculately. He was a skilled chemist, and alchemist too, if the tales of his jewels are true. (He always had a large collection of huge pearls, rubies, diamonds, etc with him, which was just as well, as he seemed to have no visible source of wealth. Nor, more strangely, was he ever know to eat or drink in company. He loved dinner parties, but only for talking.)

In the 1760s he vanished completely from society for 15 years, then reappeared in 1775, again looking no older. The first sighting of him had been as early as 1710, looking like a 40-year-old even then, so when he finally died in 1784 ....

Or did he? There were repeated sightings of him well into the next century, by which time he had already acquired the reputation of being immortal and ageless. Saint Germain liked to give the impression that he had been around for centuries - indeed, a young English nobleman called Lord Gower had already made fun of him for this way back in the middle of the 18th century.

Gower, it seemed, was a good mimic, and had one day imitated Saint Germain reminiscing about the time he had met Jesus. What kind of a chap was Jesus? Gower pretended to ask him. Oh, a very good sort of chap, he had Saint Germain replying, but very fanciful and full of romantic notions.

So I am grateful to that French lady in the train. Thanks to you, I have not only encountered a famous Frenchman I knew nothing about, but I have made the amazing discovery that when Mel Brooks and Carl Reiner invented the Two Thousand Year Old Man, they were not doing anything that had not already been done by a young English nobleman in a drawing room in Paris 200 years earlier.