After the school's last abortive expedition to the West End, when we didn't even make it to the theatre, this time we roll into London two hours early.
"Look, look a homeless!" Aidan screeches out of the window. "I told you we'd see one."
"Have you never seen a homeless person before?"
And he isn't lying. In fact, a number of these students have never been to London, which seems almost medieval to me, but there it is. And many have never been to the theatre either. "Is it true they do pizza at half time?" Meg asks.
After disembarking, we allow the students to roam free in the confines of Covent Garden's central square, while we slope off for a pint. Half an hour later, a teary-eyed Rachel taps on the pub window.
"I felt someone squeeze my bum and then I saw a weird-looking guy behind me," she sobs.
"Do you know where the man is now?" I ask.
"He's gone. I just wanted to tell an adult so I could feel normal again."
I feel like giving her a hug, but ironically it is because of people like this pervert that I can't. It's enough to make you despair that country girls going to the theatre for the first time can have their bums squeezed by phantom urban menaces.
Unfortunately, Rachel has started a trend. Hannah is also bawling her eyes out, because she left another student unattended and is now convinced that she narrowly escaped being sold into the sex trade. Changing tack, we try to usher them into the theatre early.
Except that four students are now missing. We panic and count and make everyone form orderly lines and then count and panic and count again until a black cab pulls up and the four students pop out, grinning like reality show contestants. They had taken a double-decker bus to Charing Cross and a cab back because they had never used either before. Two things ticked off the bucket list in half an hour. I have to hide a fatherly swell of pride as another teacher yaps at them.
Inside, I patrol the upper circle, confiscating several bags of Skittles to stop students taking potshots at people below. To my inordinate relief the lights finally dim. A man walks on silently, staring upwards in an actorly manner for some 30 seconds. Peace at last.
"Get on with it," bellows Meg to a ripple of tutting.
I had assumed that theatre etiquette was something you picked up intuitively, like knowing not to urinate on a war memorial. But the students whoop and shriek at every turn. A rather officious theatregoer swivels around several times. It is Friday night and I am shattered, so I decide the best option is to sleep through the whole thing and pretend the group belongs to someone else. This works surprisingly well until Aidan yells at me during the interval, "Did you shit yourself, Sir?"
After the show, 90 grinning students wait outside the stage door, refusing to leave until the actors appear. The cast come out sheepishly, to a cascade of applause and wolf whistles. Magic.
Nelson Thornberry is a pseudonym. He is a teacher at a secondary school in the UK. Read his blog at disgruntledteacher.tumblr.com.