When you stop to think about it, the British choose a pretty odd way to celebrate the birth of a Jewish prophet 2,000 years ago. It's hard to see the connection between an emergency delivery in a stable near the West Bank of the River Jordan, and an annual overeating festival followed by a word from our monarch, then several more words from James Bond. Not many Christmas trees grow in the Middle East.
Our Christmas rituals were devised by an accidental amalgam of Christian liturgy, pagan rites, the monarchy and John Logie Baird.
Of all these influences, it's striking quite how many were the creation of the Royal family, in particular Queen Victoria's Royal family. And when you talk about Queen Victoria's Royal family, you're really talking about a German family. Of her nine children, six married Germans (and the others married a Dane, a Russian and a Scot). Between the 1660 wedding of James, Duke of York - later James II - to Lady Anne Hyde, and the 1981 marriage of Prince Charles and Lady Diana Spencer, no English woman married the heir to the throne.
From the time of the Hanoverian George III, and his German wife, Queen Charlotte, royal Christmases were German Christmases. It was Queen Charlotte who introduced the German custom of the Christmas tree - then a yew tree - to Windsor Castle, dressing the branches with presents in the room of her German attendant, Madame Berkendorff.
Queen Victoria - herself half-German through her mother, Princess Victoria of Saxe-Coburg-Saalfeld - made the British Christmas even more Teutonic through her marriage to her German cousin, Prince Albert. The moment when the Christmas tree took off over here came with an engraving in the 1848 Christmas supplement of The Illustrated London News, which showed the Royal family gathered around a Christmas tree at Windsor Castle. Prince Albert even ordered the royal tree from his ancestral acres in Coburg, Bavaria.
Albert's German childhood had been a snowy one, and he introduced the full panoply of winter sports to royal life: building a 12ft-high snowman for Victoria; jingling across the snow in the family sledge; skating on Frogmore pond, near the site of what would become both his mausoleum and his wife's.
The interest in - and the influence of - the Royal family was already immense then, perhaps even bigger than now; certainly, the royal picture sold more copies of The Illustrated London News than Pippa Middleton's Celebrate.
Christmas cards, too, were made popular by the Royal family. The penny post was introduced in 1840 by Henry Cole, a friend of Prince Albert's. Three years later, Cole came up with the Christmas card, selling 2,050 of them for a shilling each. The Royal family has, ever since, dispatched Christmas cards to their nearest and dearest, the great and the good, occasionally using them as subtle propaganda devices. The royal Christmas card for 1940 showed George VI, in naval uniform, and Queen Elizabeth standing in the garden of bomb-shattered Buckingham Palace, with six workmen gathered in the crater behind them. In her widowhood, the Queen Mother took to sending Christmas cards of herself alongside her prize-winning racehorses.
In recent years, royal correspondents have decoded the cards to get a handle on what's going on behind closed palace doors. In 1986, Prince Charles and Princess Diana looked happy enough on their Christmas card, cuddling a beaming William and Harry and a rather sadder-looking corgi. By 1992, William and Harry were pictured in jodhpurs, looking as miserable as the corgi. In 1995, the year before his divorce, Prince Charles was photographed alone with his sons. By 2005, Camilla Parker Bowles was such an established part of the Firm that she was pictured at her wedding to Prince Charles, flanked by William, Harry and her own two children.
The Christmas broadcast is, by definition, a royal invention, celebrating its 80th anniversary this year. In 1932, Sir John Reith came up with a brilliant idea - not something you can say about more recent Director-Generals. He thought a Christmas broadcast would be a good way to start the BBC's Empire Service, now the World Service. For that first Christmas broadcast, from Sandringham, George V was given few broadcasting lessons, besides being reminded about the cueing light signals: flashing red for standby, permanent red for on-air. He went through a few voice tests, which was lucky - just before the real broadcast he sat down heavily in his favourite wicker armchair and burst through the seat. With admirable restraint, he said no more than: "God bless my soul."
Much of the 251-word broadcast remains familiar, particularly the opening: "Through one of the marvels of modern science, I am enabled, this Christmas Day, to speak to all my peoples through the Empire…." And the speech, co-written by the king with Rudyard Kipling, was a hit among its 20?million listeners - not including his errant son, the Prince of Wales, who chose to play golf instead.
Edward VIII's reign wasn't long enough to include a Christmas broadcast, and we all know about his brother's speechmaking difficulties thanks to the 2010 Oscar-winning film, The King's Speech. At his first Christmas as king, in 1936, George VI didn't make a broadcast, whether out of nerves, respect for his late father or in the light of the abdication; he had only come to the throne on December 11.
Again in 1938, he refused to do a Christmas broadcast because of his fear of public speaking. In 1939, with war spreading across Europe, he had little choice but to return to the microphone, much as he disliked it, confiding to his diary:
"I broadcast a message to the Empire at the end of the BBC Round the Empire programme. This is always an ordeal for me, and I don't begin to enjoy Christmas until after it is over."
At the end of that broadcast, the king quoted from an anonymous poem that he had been sent in a Christmas card:
"I said to the man who stood at the gate of the year, Give me a light that I may tread safely into the unknown."
And he replied, 'Go out into the darkness and put your hand into the hand of God.
'That shall be to you better than light and safer than a known way!'?"
In another illustration of the ballistic media power of the Royal family, the BBC was immediately inundated with requests for the poem. George VI didn't know the name of the author. Even the author herself - Minnie Louise Haskins, a Sunday school teacher and later a social sciences lecturer at the LSE - didn't recognise her own poem when it was broadcast.
But, thanks to the royal mention, the first collection of her poems was published the following year. The Queen Mother later had the poem engraved on the gates of the King George VI Memorial Chapel at Windsor, where she and the king are both now buried. "The Gate of the Year" was also read out at her state funeral in 2002.
For his last Christmas broadcast, in 1951, an extremely ill George VI had to record his message in separate chunks whenever he had the strength. He struck a sadly optimistic note:
"By the grace of God and through the faithful skill of my doctors, surgeons and nurses I have come through my illness."
Six weeks later, on February 6 1952, he died in his sleep at Sandringham.
His daughter has fewer microphone problems. As Andrew Marr revealed in his Diamond Jubilee documentary, Elizabeth II is known by the broadcasting crew as "one-take Windsor".
One of the few royal traditions that has failed to catch on in Britain is the old German one of Heiligabend Bescherung - or the exchange of presents on Christmas Eve. In her diary entry for Christmas Eve 1843, Queen Victoria referred to it by the German name, even if she spelt it wrongly:
"After luncheon, we all walked out, and on coming in, had the excitement and agitation of finishing arranging the Bescheerung and presents, which to me is such a pleasure."
Before the injection of German blood into the royal veins, the twelfth night of Christmas had been a much more significant part of the festival than Christmas Eve.
In 1601, Queen Elizabeth I even commissioned Shakespeare to write Twelfth Night, to entertain her guest, Virginio Orsini, Duke of Bracciano. Shakespeare was told that the production "shall be best furnished with rich apparel, have great variety and change of Musicke and daunces, and of a Subject that may be most pleasing to her Maiestie".
These days, the Bescherung custom continues. This year, at Sandringham, the Royal family will swap presents on Christmas Eve as they did throughout the last century, despite the tricky little impediments to harmonious Anglo-German relations in the years 1914-18 and 1939-45.
The pattern of the modern royal Christmas is set in stone. When Prince Philip missed last year's Christmas lunch due to a heart operation, it was the first time he hadn't been at the family celebrations since 1956, when he was in the Southern Ocean on HMY Britannia during a four-month world tour.
Still, not everything at Sandringham is cryonised in Victorian aspic. In recent years, at least one new royal Christmas tradition has been minted: the ritual exclusion of Fergie from Christmas lunch. Or - as the practice of disinviting unpopular relatives is known in Germany - NeinInvitenDasToeSucker.