"Time to test-drive Jennifer's new nose," announces Bob. We applaud as it débuts from behind a screen, round and red, Jennifer attached by a length of elastic. Martin's nose, a veteran in comparison, enters next, Martin in tow. "Don't laugh, Martin. Relax your shoulders," Bob commands. And to Jennifer, "You have an irresistible urge to touch Martin's elbow. But you can't." This signals the start of an improvised two-hander, the Jennifer and Martin show, comprising meaningful gazes and exaggerated gestures. At the end, Bob seems reasonably satisfied. "The beginnings of nice piece of business, there. A good dynamic."

The Circus Space, in Shoreditch, runs a series of Clown evening courses for which would-be Grimaldis pay £95. Some are actors or entertainers. Many, however, are professionals, such as teachers, lawyers, and accountants. What attracts them? According to tutor, Bob Pearce, it isn't just the prancing around in a red nose. The course can also be useful for acquiring or honing management and business skills. So what's the link between mastering custard-pie ballistics and initiating a hostile take-over bid for Glaxo-Wellcome?

"Obviously, the primary aim is creating comic characters and having fun. Along the way, the whole process of communication and creative problem solving gets explored. Clown logic doesn't see problems as barriers, but as opportunities for comedy. A clown will take the longest way round to solve a problem rather than the simplest route. It therefore encourages a different, lateral method of thinking, which can be usefully applied elsewhere."

A clown, for instance, won't waste time searching for the end of a roll of Sellotape. He'll simply cut the whole thing in half with scissors. Nor will he struggle to open a carton of UHT milk. Instead, he'll try to source a UHT cow. It may sound stupid, but, says Bob, the essence of good clowning is stupidity. Or rather, "It's about being happy with your own level of stupidity; about enjoying, rather than repressing, your latent, wackier aspects."

Mine apparently manifest themselves in the way I unconsciously hold my pen at a right-angle while simultaneously twiddling my thumb. If I work on this, Bob reckons I've got the makings of a half-decent routine. Maybe I don't feel quite ready to "come out" yet, I reply. But for those who have, what are they getting from the course?

"We're so goal-directed in our lives," says Jennifer, an ex-literary agent in her 50s. "This kind of course, where you abandon all goals and just have fun, is a corrective, highlighting the artificiality of everyday life. It's also very bonding: we're all willing each other to be funny."

Claire, a twentysomething who works at the Festival Hall, regards it as therapeutic: "I come straight from work, usually very tired. But the time I put in here passes very quickly and I emerge feeling totally energised."

Each class warms up with the sort of games we used to play at school, like tag and grandmother's footsteps. These help shed inhibitions. Next, the noses go on and improvisations begin. "The nose focuses attention on to the face," explains Bob. "When you look at something, your nose points towards it, so the audience can immediately see your thought process. It also acts as a mask, helping students to discover and become their character."

It has to be said that - for me, anyway - many of the improvised routines exude all the comedic potential of a Little & Large sketch directed by Ingmar Bergman. But many, too, show flashes of sheer brilliance. A take-off of a gameshow host, for example, conducted entirely in Dutch, has us all in stitches. Whenever gold is struck, however, Bob refuses to take credit:

"I'm just a catalyst. Everything comes from the students. I simply create the environment whereby it's safe to let it all out. We're not often allowed to make complete idiots of ourselves. Here, we've got 2 1/2 hours every Thursday night to do exactly that."