... Sooner or later, of course, all children learn that Father Christmas isn't real: it's part of the process of growing up. It may be true for some of them that Christmas is never quite as magical an event again, and I hope I'm not disillusioning any young (or perhaps not-so-young) listeners by making this point now.

In any case, in the long history of celebrating the twenty fifth of December, which by definition has gone on for the best part of two millennia, Father Christmas is a relatively recent interloper on the festive season - more venerable, to be sure, than the Queen's speech or the Nutcracker ballet or Morecambe and Wise on television, but still something of a Yuletide upstart.

But then, there's a great deal about the supposedly "traditional" Christmas which, on closer inspection, turns out to be nothing of the kind: for many of the rituals and customs that we now associate with it have been created and evolved during my own lifetime, which (I hope you'll agree) makes them relatively modern rather than venerably ancient.

Of course, the stories of the Wise Men bearing gifts, of the shepherds journeying to the manger, and of the virgin birth in the stable at Bethlehem, are as old as (if not older than) the gospels themselves. But whatever its subsequent religious connotations, the origins of Christmas are far from being exclusively Christian.

In the northern hemisphere, the cold dark days of December and January have always been a time when light and drink and food and cheer are more necessary than ever: hence the Roman feast of Saturnalia, and the Germanic celebration of Yule, which were gradually merged with the Christian story of the Nativity between the fourth and the sixth centuries.

From then on, Christmas expanded and flourished across the medieval world, and by Tudor and early Stuart times, there were often lavish junketings, with presents, plays, games, feasts and processions - but not with Father Christmas.

This may seem a festive celebration closely akin to those that go on in our own time, but there was a sudden and abrupt hiatus in the mid seventeenth century. For the Puritans deeply disliked the cult of Christmas: they equated it with the twin evils of popery and royalty, and they feared it meant people might enjoy themselves too much.

As a result, this once-elaborate festival withered away, so that by the early nineteenth century, the critic and writer Leigh Hunt thought Christmas was "scarcely worth a mention". And this was a widely shared view.

At about the same time, the committee of the Carlton Club, which in those days ran the Conservative Party, arranged an ordinary business meeting on Christmas Day itself, on the grounds that the members would be both able and willing to attend - not perhaps a practice that that David Cameron should consider reviving now.

As we know it and celebrate it today in Britain, the traditional, "old fashioned" Christmas, is largely an invention of the last century and a half. The first major phase of innovation came during the 1840s, when cards, mistletoe, pantomime and presents were introduced or in some cases re-introduced.

They were nothing to do with Britain, but they helped remind Albert of the German pine forests where he had grown up. The result was a revival of the British Christmas as a great expression of middle class family values, exalting social harmony, stressing (however implausibly) universal participation, and acclaiming charitable gestures by the rich towards the poor. ...