ON A mild weekend in mid-December, I’m standing high-up in Colchester’s former Co-op Bank just off Eld Lane, staring down at Colchester. It’s relatively quiet up here. Down below, in the gloaming of a late Saturday afternoon, festive madness has engulfed the town and high-speed shopping is in progress. “They’ll never think of looking for me here,” I say to myself, taking one last look across the architectural soup which is Colchester’s skyline.

I am upstairs at the former bank because it is currently home to Slack Space, an inspired scheme which allows redundant or unused commercial buildings to be made available to hard-pressed artistic types for their exhibitions, workshops or, in this case, rehearsals.

We’re two floors up in this chilly early twentieth century office building. With me is Jeanette Lynes, a Colchester music organiser and singer. We have temporarily joined forces with I Hear Voices, Colchester’s most-unhinged, and possibly its most-inspired, theatre company.

Their seasonally-affective play is entitled Bentley Strangetrousers and the 12 Plagues of Christmas. I don’t know any of the company members very well, but having seen one of their productions earlier this summer, in the heat of my enthusiasm I offered “Look, if you ever do one of these again, do call me and . . .” You may guess the rest of the story.

I am tasked with performing one comic song on piano, accompanying Ms Lynes on a second song, and also have a couple of small speaking parts. Just to add a frisson of nerviness to it all, at time of writing the play’s script is still being edited by Damien Bell and Darren Gooding, its two writer-directors.

In addition, a necessary last-minute rehearsal has been fitted in for the day of the show, a mere five hours ahead of performance. Lastly, after the performance finishes late this afternoon, I must ready myself for the Christmas Poetry Bash which John Cooper Clarke, Luke Wright, Ross Sutherland and I perform every year. That’s one last rehearsal here, followed by two separate shows – both of them at Colchester Arts Centre. Probably be okay. Won’t it?

I Hear Voices are a theatre company for our shoestring times. They exist without a permanent base, are self-financed and, I suspect, don’t receive much encouragement from any arts facilitators. By arts facilitators, I’m talking about those official bodies in charge of funding who begin all their mail-outs to artistes with the winning phrase “Dear Creative Practitioner”.

The I Hear Voices Theatre Company, however, have developed their own feral way of doing things, which is refreshing and funny. They stage their plays as if they were being recorded live for radio – rather like The Goon Show or Round the Horne – later putting them up online as podcasts.

Go and see them, as I did, and you find yourself looking at something which has probably not been done much in the theatre since the 1950s or ’60s. The actors and actresses read their parts into microphones. The sound effects are created live by a small Foley team, who remain on stage with the cast. There is also a warm-up man before the show. During the performances, there may be re-takes, allowing them a necessary margin for errors. It’s a show where the audience, charged with playing the part of an audience, quickly becomes included. It leaves room, therefore, for mistakes to be safely accommodated. There are no complex scenery or costume changes.

It is guerilla theatre, which has almost certainly arisen in the face of its own adversities: lack of cash, a boring and predictable mainstream, and the fact the company is not London-based. Because if you don’t prostrate yourself before the Great God London, then, in England at least, you will be ignored by the media and, as a consequence, prove invisible to much of your target audience.

And yet the I Hear Voices Theatre Company aren’t angry radicals. Their production, centred on the blunders of a spoof ’50s detective, Bentley Strangetrousers, is in a fine tradition of Great British silliness. There’s no swearing, and any innuendo is so daftly obscure that you could safely take your children to see it.

Another enjoyable aspect is being hurled together with a group of people, most of whom I hardly know, in a collective flight of fancy taken onto the stage in a semi-prepared state. Although I don’t know my fellow cast members, I get the feeling some are fearfully clever. Female lead/arch villain Mary Bollan, for instance, is a former County High girl. I discover that as well as being a good comedy actress, she works as a PA for two barristers in London. She can play a few instruments, she’s studying modern languages – oh, and she seems to know the names of more medieval siege engines than I do. That’s pretty �ber, isn’t it?

This episode of Bentley Strangetrousers will enjoy its debut outing, possibly its only outing for now, at Colchester Arts Centre today. The company are augmented, just for Christmas, mind, by Jeanette Lynes, and your correspondent here. Alas, I shall never play The Dame.

Bentley Strangetrousers is at Colchester Arts Centre today, for one afternoon only. Doors open 2pm. Tickets, �5, available on door or ring 01206 500900.