The curtain falls. The audience rises to its feet as one, a feat made easier because it is an audience of one.

That old joke is rarely true of school shows: parents generally flock to them. As the spring term ended, I, like many other secondary headteachers, was still reeling from that last big show before we were forced to concentrate almost exclusively on the long summer exam season. But for many staff in primary schools, the last few weeks of the year are the time to watch children take to the boards. What fun.

We in secondaries have felt an absence during the past term. When there isn’t a production in preparation, our schools seem the poorer. A sense of purpose, excitement, joie de vivre and trepidation pervades even the largest institutions in the run-up to a performance. This is true of musicals more than straight plays (the musicals always sell out, while we have to drag audiences to Shakespeare productions).

Shows generate a magic that permeates school life. When I pass cast members in the corridor, we share banter about how tired everyone is, last night’s comical near miss and how we think tonight will go.

Pantomimes and musicals are a distinctively Western phenomenon. Not long ago I was describing my school’s performing arts programme to our partner school in Tangshan, China: my hosts struggled to understand because their culture doesn’t have an equivalent.

Nonetheless, British-style schools overseas rightly insist on exporting that bit of Western culture. A friend of mine was amused to see Snow White and the Seven Dwarfs performed as a Christmas show at a British school in Thailand. How would Aladdin go down at a school in the Middle East, I wonder?

The more demanding the show, the narrower the boundary between ambition and disaster: pitfalls are abundant. When I was a music teacher in the 1980s I co-wrote a musical. At the climax of the opening night, as the heroine prepared to shoot dead her unfaithful lover, the gun jammed. A painful silence was broken only when my co-author slammed the handle on the fire door, cursing as he rushed out into the night air. The leading man eventually sank to his knees and died of an apparent heart attack - not the denouement we had planned.

The following night we had a contingency plan in place. For a moment the gun seemed about to fail once more. At last it worked, but not before the drummer had rapped out a shot and several stagehands had added their own substitutes. As a result, the villain appeared to expire in a burst of machine-gun fire.

Losing the plot

I still occasionally contribute to my school’s shows by playing in the band, although I don’t overestimate any credit I might gain. One oblivious actor complained after a week’s run, “You’d have thought the headteacher might come to the show just once!”

Musicians are also at risk of theatrical disaster. In a recent West Side Story, during the scene where Riff and Bernardo are stabbed, the bald head of the drummer in the pit below was sprayed with artificial blood. When we did Les Misrables, the director insisted on a West End-style turntable: whenever it spun, it sprayed the band with chewed-up plywood.

Then there’s the issue of subject matter. Grease is a curious hit, hugely popular despite a questionable storyline that suggests a girl becomes acceptable to her peers only when she dresses and behaves in a way that schools would deem entirely unsuitable.

The car is a major focus of Grease. We loaned our school theatre to a neighbouring secondary and there was heartbreak when their beautifully constructed Cadillac wouldn’t fit through the stage doors. By contrast, another production demonstrated the ultimate low-budget solution: the cast formed the car, rear fins and all, using their bodies. It was inspired.

Similarly, Cabaret is a powerful musical, but school productions invariably give rise to conflict when directors insist on dancing girls’ costumes that are little short of indecent. (When my great-aunt saw an early production, she remarked drily, “In my day we’d have called that a leg show.”)

Why do we put ourselves through it? I had to restrain a colleague at a fraught final rehearsal when one of his actors asked, “But, Sir, what’s my motivation?” He replied through gritted teeth, “It’s this: if you don’t do it, I’ll throttle you!”

We do it because it matters. Few collective school undertakings are so utterly creative in preparation and execution.

Even relatively modest shows can have a huge impact on school life. Recently a colleague of mine staged Willy Russell’s Educating Rita, a full-length play but a two-hander. It was extraordinary to watch two teenagers bring disillusioned university lecturer Frank and naive, irrepressible Rita to life. The play was an education in itself. That’s the point. We make great demands of our young actors, and the route to the performance is a learning, even life-changing, experience.

I still put myself through the pain. In 2012 some colleagues generously staged another musical I had written, set in a dystopian, post-apocalyptic Britain reshaped by rising sea levels, where displaced children were regarded as a problem to be eliminated. Fittingly, the school was struck by a major flood two days before opening night. Staff and students pulled together heroically and the show went ahead - better than I dared hope.

No, I simply can’t do without the agony and the ecstasy. And I’m quite sure schools can’t either.

Dr Bernard Trafford is headmaster of the Royal Grammar School in Newcastle upon Tyne