Should this fail to discourage you, it’s the Christmas cards which will drive you to drink.

For the past week or so I have been engaged in a life-or-death struggle over the design of cards to be despatched by members of the London Assembly. The members have been offered a choice of five photographic images of London with the words “Seasons Greetings” on the cards.

None carries religious imagery; many would go to people who are not Christians, and it seemed a little insensitive to insist that they should display a cross or a baby Jesus among their greeting cards.

Naturally some people were not pleased. One political team - no prizes for guessing which - condemned the lack of traditional spirit and commissioned its own cards. Fine, except that these too failed to contain any Christian symbol - though it did put the Norwegian fir, a widely used pagan emblem, centre stage.

This little episode illustrates two big issues for a 21st century nation. First, at what point do the claims of diversity endanger the idea of a shared culture? For my money, we need to go a step forward on this, but not in the direction you might expect. As you sit down to your festive fare, reflect that here are two varieties of multi-culturalism. The metaphor for one is salad - a brightly-coloured mix of identifiable, separate ingredients, in the same bowl.

The other is soup - a combination of tastes, most of the separate flavours invisible to all but the most discerning palate.

Ultimately, I am a salad man myself; I like the essential egalitarianism of it, allowing the smaller ingredients to have a visible presence. In tomato soup, or borscht, however dlicious it is, everything else is swamped by tomato or beet. I fear that in Britain we are choosing soup.

In Christmas card-speak, we are embarrassed into a sort of soup-like seasonal secularism; we haven’t yet brought ourselves to accept that all religions can be celebrated by those not of the particular faith, but we don’t want to be seen to privilege our state religion.

I agree with those who say that we should emphasise the Christian-ness of Christmas - but only if we are also ready to recognise and celebrate the Muslimness of Eid or the Hinduness of Diwali equally. And don’t get me started on disestablishment of the Church of England.

The other issue is how to reach a decision in a public body. Anyone who has ever shared a car or a home with strangers, or perhaps even a staffroom, knows the principal sources of conflict: air vents or open windows; Corn Flakes or Shredded Wheat; pierced tongues or not. In the family you can settle in the traditional way - parents try to decide, fail to agree and the kids do as they wanted to in the first place.

Unfortunately, when the taxpayer is stumping up, strong government demands an answer. There are two ways to solve this: dictatorship or democracy.

On big matters, the answer is usually pretty clear: it’s whatever will alienate the fewest voters. We tend to call this democracy, and elected representatives tend to have confidence in it.

However, it doesn’t work so well when nobody cares. The voters could not give a toss whether the Prime Minister’s curtains are green or hibiscus pink, so long as they don’t have to pay extra for them. And it’s here that politicians clash most viciously.

I should have seen the Christmas card row coming. This was one where the firm smack of dictatorship should have come into play. I’ll know next time. Merry Christmas.

Trevor Phillips is chairman of the Greater London Authority