Contrary to what you may have heard, an actor's worst nightmare is neither forgetting lines nor bumping into the furniture. No actors worth their salt get through a single performance without forgetting their lines and bumping into the furniture. It's one of the first skills you learn at drama school. No, an actor's worst nightmare, as I'm sure the estimable Michael Simkins will have explained in his Guardian columns, is you.
If we could only do the play the way we want to, without worrying about the audience turning up late, coughing, laughing in the wrong places, not laughing in the right places and generally intruding when we're trying to get on with some work, people ... well, we'd be making TV programmes.
But surely theatre is all about that live, unforgiving spontaneity. Imagine if everything was as predictable as my using that tired "roar of the greasepaint, smell of the crowd" cliche somewhere in this piece ... here, for instance.
This week saw a second theatre heavyweight stepping in to curb your bad behaviour in our workplace. Kevin Spacey, now the artistic director of the Old Vic, has followed in the footsteps of the actor Richard Griffiths by threatening to ban owners of disruptive mobile phones. He also railed against "people who open candy bars thinking if they open it slowly it will be less annoying than if they open it fast".
Now in defence of the sweet-eaters, I should point to a recent scientific study that encouraged a hundred or so, shall we say, porcine cab drivers to eat sweets regularly as an aid to weight loss. It worked, bizarrely. And since some of the sweets were gobstoppers, it had the unexpected benefit of denying various rightwing political groups the oxygen of publicity. So it's just possible that the sweet unwrappers are watching the play quite intently, but watching their waistlines even more so.
But when it comes to theatrical etiquette, there are two prevailing opinions: those who think that the whole notion of sitting quietly and not stirring till they bring out the tray of Loseleys is a 20th century affectation, and that the odd brawl was meat and drink to Shakespeare and Garrick; and All Normal People, who figure that having remortgaged the house to buy tickets it might be nice to be able to hear the play.
The latter view does have its over-zealous adherents, such as the man at the opera who asked me to remove my watch because its tick was out of rhythm. But by and large, most of us tolerate being made to sit so close to strangers that you can smell the tea on their breath, so long as they shut up and sit still. We'll even put up with some disruption, if it's obviously accidental. My mother once tried to take a surreptitious swig from a bottle of water to stop a coughing fit. Not realising, however, that the water was carbonated, she sprayed the woman next to her with a thoroughness that would have delighted fans of Charlie Caroli. The woman simply smiled and carried on watching.
Performers, however, never forget the times when you ruin it for us, even though it happens more often the other way round. Al Murray remembers being upstaged persistently by a man who took his false teeth out and pretended they were "laughing". Armando Iannucci once arrived for what he thought was a reading, but the audience thought was a disco. A near riot ensued between drunk and frustrated disco divas and devotees of wry satire. He didn't stay to see who won.
My weirdest experience of persistent disruption was during a performance of a musical I was in at a West End theatre. It baffled us all, until front-of-house staff discovered that a couple were having sex in the royal box. Throughout act one. Maybe, like Kevin Spacey's sweet unwrappers, they thought that if they did it slowly, it would be less annoying.
