Christmas is coming, and with it the Christmas concert. It's something I always look forward to. Our school has a reputation for the creative arts, and my talented staff always manage to delight our parents with a colourful hour of festive music, poetry and drama. So high has the standard become, our shows are like West End productions.
And therein lies a problem, because we worry about what might go wrong.
Will the CD player pack up or skip a track? Will the scenery collapse? Will a mobile phone ring ... and if it does, the owner is bound to be sitting in the centre of the hall where nobody can stop the culprit having a loud conversation.
The ritual starts with an activity we call "seating the mothers". Some are ... how can I put this delicately ... generously upholstered. On the other hand, our school hall is small, and since many parents come to our concerts we have to use the children's chairs.
Years ago, parents would wade in among the chairs, scattering them as they sought a place to sit. They'd also bring snacks, umbrellas, thick overcoats, and often a baby who would cry throughout most of the show. One year, a mother brought both her current boyfriends and a six pack of lager.
We've got all that sorted now. The rules are strict and we use a large school governor to regiment the parents into neat, tight rows.
The children usually perform faultlessly, although we do have our moments, such as the year when the Angel Gabriel made an impressive entrance ... only for his wings to become stuck firmly in the wooden structure of the stable.
As he moved position, his costume and wings remained on the stable and he greeted the baby Jesus clad only in a vest and underpants. Horrified, he sought refuge behind the ox and ass.
Jason, on the other hand, wouldn't leave the stage. His teacher knew he had talent, but had struggled to convince him he was right for the main role in the class play. But once he'd experienced the thrill of performing to his mum and auntie, who applauded and videoed his every move, he refused to get off, repeating his song ad nauseum and ignoring his teacher's increasingly curt insistence that his time was up.
Finally, she climbed on stage and led him firmly off, while he waved enthusiastically at his adoring relatives.
Sometimes, it's the props that seem to have a life of their own. Santa's toy box was a prime example. Beautifully constructed, it took centre stage ready for the Chief Elf to open, whereupon Santa's toys would come out and perform their actions.
But when the time came for the lid to be lifted, Alfie seemed to be struggling. "Open the lid, Alfie," urged his teacher from the wings. Alfie fiddled frantically. "Open the lid, Alfie!" implored his teacher again.
"I'm trying," the put-upon Alfie announced loudly and rather irritably. "But the bloody lid's stuck!"
If it isn't the props, children or scenery, the hall itself can mess things up. When the roof was being repaired, we suffered the worst thunderstorm of the year right in the middle of the Christmas concert and the rain was soon dripping into the laps of the audience.
I stopped the show, shuffled the audience around, handed out waste buckets to catch the water, and told the parents that footling little problems such as this certainly weren't going to stop the performances of their wonderful children. There was a rousing cheer from the parents, and the collection of money after the show was our best ever.
Mike Kent is headteacher of Comber Grove Primary, Camberwell, South London.