The day I danced for a place in Danny Boyle's Olympics spectacular

Badged up like cattle at a county fair, I am 70 places from the front of a 200-person conga line, obediently following a purple stripe marked out on the floor of a dark, cavernous hall. Hyper-bubbly "dance captains" on elevated platforms bellow instructions: "Row the boat. And back. Double time. Reach up. And forward. Dust yourself. Dust yourself." For many of our number, the decision to audition to dance at the Olympics opening ceremony was a consequence of those coveted preliminary round Taekwondo tickets just not coming through. But others evidently see it as their ticket to the big time. One barked instruction divides us: "Freestyle!"

A younger, bestubbled gent in red leggings throws his arms upwards and pirouettes with such force he is at risk of ending up in Australia. The dance captains crane their necks, inspecting the masses and making marks on their clipboards and I try to remember what I do at weddings, but the bar has only bottled water on offer. The Olympic dream may already be over.

When David Cameron more than doubled the budget for the Olympic and Paralympic Games' opening and closing ceremonies in December, from £40m to £81m, a call went out for more manpower. We are those swollen ranks. We are met at the Three Mills Dance Studios in east London, next to the Olympic Park, where for months the ceremony director Danny Boyle has already been planning the greatest show on earth. A few weeks ago, Boyle announced the ceremony would be called "Isles of Wonder", inspired by some poetic lines in Shakespeare's The Tempest.

A short video of rehearsals thus far features dancers with giant golf balls for heads, "zorb" balls being pushed uphill and what looks like an old man in a neon bed. On the floor of the giant studio is a vast grid. "It's like a big game of Battleships," Steve Boyd says. He is a Canadian "mass-movement specialist". This grid, evidently, is the secret behind how you make thousands of people fashion themselves in seconds into Olympic rings, St Paul's Cathedrals, Routemaster buses, or whatever it is that Boyle has planned.

Auditionees are asked not to divulge details of what they have been asked to do. It will not come as too much of a shock though, that there is a straightforward routine to be learnt. I am definitely not the worst, but red-leggings man is already adding his own interpretation to the moves. Later he describes himself as a "professional dancer". It seems unkind to point out he is auditioning for a six-month gig for which there is no fee. That Usain Bolt might be coming to Stratford for any reason other than to watch him hand jive dressed as Shakespeare doesn't appear to have occurred to him.

"We put in for tickets for the opening ceremony, like everyone else," Susan, from Kent, says. "But we didn't get them. We didn't get any. I just really want to be a part of it. It's once in a lifetime."

After going through the routine for a final time, people with specialist, and secret, performance skills, are asked to stay behind briefly at the end. Neither Trivial Pursuit nor Super Mario Kart are among them so that's me done.

But the waiting doesn't last long. Eight hours later and I am invited back to a "role-specific" audition. Sir Steve Redgrave is still the current favourite to light the Olympic cauldron, what with his five gold medals. Expect to see those odds come down in the near future.