Part way through, the four girls on stage lost track of their words. Professional actors would no doubt have employed some skilful fudge, and many adult performers would have been in a state of deep panic, but these four simply walked off the stage, held an animated conversation in the wings, and then returned as if nothing had happened. It was done with great aplomb and nobody minded in the least.
The four girls will recall that event in the middle of the next century, when they are in their 60s and beyond. Of all the things that happen in a busy school life, it is often the unexpected and hilarious cock-ups at concerts, plays and performances of one kind or another that stay with us. Most adults who ever took part in any public stage show as a child have similar vivid recollections.
I remember as if it was yesterday the unexpected ending of our school day version of Macbeth. The high point of the play comes in the very last few moments when Macduff enters carrying Macbeth's head in his hand. Unfortunately the art teacher had spent all term lovingly crafting this grotesque severed head and we had never had it for any of the rehearsals. It only became available for the first public performance.
Macduff strode on to the stage, clutching the fearsome looking gory head, skilfully constructed of wire and papier mache. Parents and actors alike froze, mesmerised, as he moved dramatically to the centre of the apron stage holding it at arm's length.
We members of the cast knew that, for the first time, he would be able to cast it contemptuously on to the ground and speak some of Shakespeare's most dramatic lines. He took a deep breath and put on the nearest a schoolboy will ever get to a ferocious look. "Behold, where stands th'usurper's cursed head", he thundered, before hurling the elaborate prop to the floor.
Bonk, bonk, bonk. The wretched object bounced mightily across the stage, down the steps and then rolled eccentrically past the audience. "Er, several rows into where the parents are sitting, methinks". Years afterwards I would meet fellow pupils who would ask if I remembered how audience and cast were convulsed at this memorable event.
A curriculum for the 21st century needs to be wider than the subjects on the timetable, important though these may be. Extra-curricular activities can make as much impact on children as what happens in scheduled class time. Many of us are grateful to our teachers for skills and knowledge we acquired informally. Photography, music, sport, drama, are just some of my own adult interests that were introduced by teachers.
It is partly the relaxed atmosphere that helps make the impact. Conditions for learning are often at their best - volunteers instead of conscripts, high levels of interest and enthusiasm, purposeful rather than, as some children would see it, pointless activities. One teacher I knew used to run a very successful fishing club after school. It was only when he started to teach pupils how to cast a fly during his French lessons that parents got upset.
In most countries there is no tradition of extra-curricular activities. Sadly they also fell into decline in Britain during the 1980s. Many teachers, having given their time freely for years, resented the way they were being treated by the government, so they withdrew from them. Goodwill is like the helium in a balloon. It is usually invisible. only when it is removed can you see what it actually did.
Fortunately there is now a revival. The charity Education Extra (17 Old Ford Road, London E2 9PL), another brilliant idea from Michael Young, the founder of the Consumers Association, has raised thousands of pounds to help fund out-of-school ventures. School inspections increasingly include references to extra-curricular activities in their reports. It is an important step towards a broad, rather than a drearily narrow view of education.
Some schools have still managed to revive this broader vision of learning in the most unlikely circumstances. One old lag, who boasted proudly that the only extra-curricular activity he was prepared to supervise was a "wash sir's car after school" society, cheerfully organised a chess club after skilful persuasion by the head. In areas of high crime and danger to pupils, there are examples of children being escorted home in groups by adult volunteers, so that their parents need not worry about safety.
Returning to drama as an extra-curricular activity, it always strikes me as bizarre that we expect children at key stage 3 to have a mature understanding of a Shakespeare play, yet relatively few ever have the opportunity to enact it in any serious and sustained form. It was only when I turned up for the rehearsals, lunch times and after school, that I really appreciated what on earth Shakespeare was on about in Macbeth.
The difference between living the play out of lesson time and doing the classroom version of it was immense. If I had only had the latter I would have hated it. It is the same with other extra-curricular activities. Music out of hours was always more fun than classroom music. Seeing teachers as informal, often funny human beings, made more impact on me than the ritualised versions of them.
So what part did I play in Macbeth? The second witch. It was the eeriest experience of my young life, prancing around muttering threats and trying to frighten people. Only when I later met various education ministers did I realise where Shakespeare must have found the inspiration for his more sinister characters.