Spectator: Lucy Baring

When my brothers asked their girlfriends to marry them, they had already asked the only question that really mattered. Forget ambitions, dreams, religious beliefs, whether they'd have children. Would their beloved allow the Christmas tree to be decorated in silver, only silver, non-negotiable? I suspect the girlfriends thought they could say yes and get their red or gold baubles on the tree in due course. I think both my sisters-in-law would admit they underestimated on this.

It started when we lived in Germany as children. The Germans, of course, invented Christmas and they're really the only people who know how to do it, according to my mother. She bought suitcases full of drops and balls and fircones and acorns, all silver. And lametta. Lead lametta. Most of these decorations have lasted the 40 or so years since then, but she's down to her last strands of the weighty lametta. When we take the tree down, we have to carefully lift the silver strands, place them in 40-year-old tissue paper and lie them gently in a box that once housed Embassy cigarettes.

A couple of years ago, some German friends sent me lametta. But I'm afraid it doesn't match up to the original, being lighter and prone to frizziness. The real thing is heavy and drips elegantly from the twigs. Or not. Lametta is a Marmite thing and I can't persuade my children to love it. We spent our first married Christmas in New York, on the basis that, from then on, we would ping-pong between families. We marvelled at the Rockefeller ice rink; Zam was picked out of the huge congregation at St Patrick's to hand round a collection plate I've never seen so many $20 bills. It even snowed. But, deep down, I knew it wasn't a patch on Munich. Germany actually smells of Christmas.

The next year, we had our first tree. I went to Homebase and bought five boxes of silver baubles. A few days later, I saw some silver icicles in a local gift shop. Zam asked about tinsel. We never have tinsel. He laughed at the lights (fake candle style, white bulbed). We used to have a mixture of these and real candles as a child-it was a great moment when they were lit at teatime, my father on hand with a jug of water. A passionate fan of the silver theme, there was a disastrous year when (as a surprise), he sprayed the whole tree with fake snow, which made the decorations go a nasty yellow within days. My mother barely forgave him.

The years roll by, and I keep adding a small box of something to our stash. I've found acorns and fircones, although they're cruder than German ones. I've experimented with silver birds and even added snowflakes. I explain the rules to the children. Small things at the top, big at the bottom. Don't overcrowd the branches. Lametta goes on last. There are rows and tears. I tie on packets of sweets (only those with silver foil, so it doesn't matter if nobody likes the contents). This is not a joyful family occasion-it's a highly disciplined operation.

And then, somewhere along the line, I fell in love with some glass drops in an antique shop. These are blue, green and amber and I have an overwhelming urge to put them on the tree. Which is like saying I'm changing my name. The children stare at me. I tie the drops on with black cotton and stand back to admire. Absolutely not, they shout. Stubborn and contrary, I begin to suggest that some colour might not be a bad thing. In fact, now I long for colour and chaos and homemade horrors created from loo-roll tubes (which I've discreetly binned in the past) and I'm even horrified that the children feel they must ask me where they should hang a certain size.

But the brainwashing runs deep. Very deep. We're all still negotiating on lametta-currently compromising on one year on, one year off-but nothing else has changed. If I ever have a daughter-in-law, I suspect I know what her tree will look like and I really, really hope I'm wrong.