Watching your child perform in the annual nativity play is one of those precious parenting moments. Picture: Timothy Bernard

London - Well, the Pope may have cast doubt on the validity of the ox and ass around the manger, but - be under no illusions - you must not. Neither must you carp about the presence of a rabbit, hamster or, frankly, pantomime horse. Because all these creatures, and more, will be present at your local primary school nativity play, and must be taken seriously.

I am something of an expert, having experienced more than a decade of them. Between them, my four children have played everything from the Christmas Rabbit to Little Blue Star (also unsanctioned by Pope Benedict). In my view, nativities can be the theatrical event of the year. They are memorable and wonderful things. They are short, with a script which everyone knows and huge scope for improvisation.

However, there are watchwords which the dutiful parent would do best to heed.

First, do not laugh. Thirty children filing solemnly past in star costumes with their heads poking through the uppermost point of the star is not funny. A Wriggly Nativity is not Cole Porter, but if your child has learned the opening stanza, “Wriggly Nativity, Wriggly Nativity/ No one's sitting still”, you must not ingest it alongside gales of laughter. Nor is it funny if anyone's trousers fall down. Last year, my son Lucien was cast as Joseph. Worried about overheating, I tried to encourage him to wear his biblical gown commando style, as it were. “I bet the actual Joseph didn't wear underwear,” I said. “No, Mommy. I must wear pants,” was the dignified response.

Second, turn up on time. Forty minutes before is best, to scupper the parents who will bag the first three rows and erect large tripods bearing full-scale television cameras.

Third, wear waterproof makeup. Nativities might be unintentionally comic, but they are also titanic-scale tear-jerkers. I usually start sobbing while still fighting for a seat in the front row. By the time Away In A Manger is sung, and we all know it will be, I and my mascara are beyond saving.

Fourth, watch out for the innkeeper. The cautionary tale is of the small boy demoted from Joseph to innkeeper, as a punishment for being naughty.

He appeared to take the rap calmly. But on the day, in front of the entire school, he took his revenge. Mary and Joseph having turned up, knocked on the door and made the famous inquiry, the scamp thought he would rewrite the Bible. “Yes, of course I have rooms,” he announced. “Loads of space here! Come right in!” - The Independent