Most things you need to know about staging large events can be learned from This Is Spinal Tap. What event producer hasn’t turned up on site to find some equivalent of a 18-inch high Stonehenge set, because someone misread the plans?

I had my own Spinal Tap moment the other week. For those who haven’t seen the film, here’s where the hyped-up band gets lost in the subterranean labyrinth on the way to the stage:

In my own version, hosting a presentation in a very large auditorium, I had a 45 minute lunch break to get AV crews sorted, panel briefed, run sheet understood etc. With 10 minutes to showtime, it was all under control. At that point, I decided the professional thing to do was take a pre-show visit to the gents’. I headed for the exit doors underneath the raked seating.

The convention centre has gigantic airlock doors out of Battlestar Galactica. You push a large button on the wall and the first door opens. You enter the airlock and push a second button. The next door opens and releases you into the netherworld corridor a level down from the lobby. Being an environmentally responsible convention centre, the lights were off. I stumbled around in the semi-darkness, and finally found the bathrooms. Locked. I pushed the button to get back into the auditorium. Nothing. One-way, no-entry doors.

Visions of hearing the MC intro me, and nobody can hear my door-pounding and screams through the airlock.

Finally, with about a minute to go, run a hundred metres up stairs and push my way through a queue of audience at the door. Get to stage huffing and puffing. “Hello Cleveland!”

After the show I learned there’s an executive-class bathroom just backstage. It’s the little things that get you.