Tim Etchells on performance: Virtual events occur in spirit on a mystic river

"When's Michael Caine arriving, then?" was one of the questions we hadn't really anticipated. It's true that my booklet – distributed on the banks of the Thames recently as part of the event A River Enquiry, for the mayor's Thames festival – had explicitly stated that Caine would be there, "re-sinking a scale replica of Atlantis". But most people had figured out from the tone that the events in my brochure, which I'd named "Cold Water Fun", would not really be taking place as advertised.

There were certainly no crowds milling at the appointed hour to see Boris Johnson dropped naked into the river from a helicopter in the "SPLASH CONTEST", and no one formed lines later that afternoon to watch "beggars from the eurozone" perform poems to the river in cockney rhyming slang.

Over the last year or so I've done a series of related works, creating pamphlets to announce – often in overzealous capitals and small print – the dates, times and locations for imaginary, scurrilous and often impossible events. The first booklet, produced for the Frascati Theatre in Amsterdam, promised among other unlikely things a nine-hour apology from Tony Blair concerning his conduct over Iraq. More recently, potential punters in Paris were misled to expect the appearance of "biologically female" strippers and a "reflationary discothèque"; and up in Edinburgh last year, at Forest Fringe, a few sorry souls searched in vain for a genetically enhanced arm-wrestling contest in which Bob "the octopus" Brown was slated to take on Karl "the monkey man" Malone.

Back in London, the delight people seemed to find in my Cold Water Fun booklet came from its ludicrous disruption of the proper and the everyday. Standing on the banks of the Thames in the sunshine, people could look out at the serene river and imagine it filled with a replica Spanish armada in combat with Sudanese pirates.

Mimicking the contemporary appetite for reality as cruel spectacle, parroting phrases from tabloid headlines, internet spam and talent-contest announcements, the booklets contained more than a whiff of the unsavoury. The promised mix of theatrical performance and real-life spectacle mirrored our contemporary media landscape, where footage of distant disasters appears alongside fake paparazzi shots of minor celebrities having drinks with TV-coached politicians. Reality, we can say quite surely, is not what it used to be.

As a writer and producer, what excites me about creating virtual events is that you can pick your cast and locations without the concern for practicalities or budgets. If you want Demis Roussos singing Agadoo from the top of a blazing Houses of Parliament, you just write it and it's happening. If you want a debate between Pete Doherty, Charles Dickens and Robinson Crusoe, that's also fine. No matter if Doherty's in rehab, Dickens deceased and Crusoe fictional – they'll all be there without question.

Researching for Cold Water Fun, I was also thrilled to find a slew of material on London's historical carnivalesque past, specifically related to the river. I especially enjoyed accounts I found in history books of the more or less spontaneous frost fairs which took place on the frozen Thames from the 1600s onwards. Elephants were led across the ice, dancing bears and dog-fights abounded, and you found stalls of different kinds as well as puppet shows and carousels, all presented on what a contemporary commentator referred to as "the great river become a stage".

I loved imagining this transformation that the ice must have brought to the capital – stopping the river traffic and turning the working Thames into a party venue, a place for marvels and an arena in which to earn a hasty shilling. Climate change is certainly heading us in the opposite direction, but a frozen Thames would be a great excuse to stage that sliding contest, imagined in my booklet, for real.