Dom Joly: Roll cameras! Roll downhill! Roll in the money!

Oh the perils of writing about anything .... A couple of months ago I was asked whether I'd write a little piece for a book called Modern Delight. It's an update of a collection of short essays that J B Priestley published in 1949, called Delight.

The original was about the little things in life that caused even Priestley, a self-confessed "old monster", to stop and smile. The book was filled with his musings on themes universal, personal, eccentric and everyday, from streets like film sets and Sunday papers in the country to quietly malicious chairmanship and frightening civil servants. The new book is for "charidee" (much as I don't like to talk about such matters), so I agreed and wrote a little piece about how I loved rolling down a particular hill behind my house.

I sent it in and forgot all about it. It's one of the joys of writing, you can let your imagination flow and not let nasty things like reality or details get in the way. Not, that is, until someone rings you up and tells you how much they love your piece and how they'd so like to come and film you rolling down a hill ... for "charidee" of course (something I rarely mention).

Rashly, I agreed and that's when reality kicked in. Firstly we had to find out who the hill belonged to and whether they'd mind some idiot rolling down it for "charidee" (did I mention this before?). The owner was kind enough to consent. Next we had the problem of weather. I wrote the piece in spring (spring roll ... geddit?) when the hill was lush, verdant and comfy and the skies were sunny and blue.

The day the crew arrived it was pouring with rain, the sky was black as coal and I really didn't feel like doing any rolling whatsoever. Everyone, however, was on a tight schedule so off we trooped to the famous hill. This was when the final and most important problem reared its ugly head. In the period since those heady days of spring, the hill had been home to a large herd of cows (the killer cows that I've written about before – the ones my wife is terrified of). The cows had gone but they had left copious proof of their presence all over the slope. I hadn't even considered that this might be a problem.

I stood in the rain at the top of the hill while a bemused camera crew tried to mark every single cowpat on the hill in an attempt to make a path for my roll.

"This is seriously your delight?" asked a bemused and shivering assistant director. "It smells really bad out here," said another obvious townie in full Carhaart. I was also starting to shake with cold and even my two dogs indicated that we should be heading back home, and sharpish. This, however, was a "charidee" shoot and I was not going to let down a good cause.

A cow-pat-free path was finally marked. A couple of locals wandered past and shook their heads in wonder at what a stupid life I lead. "Camera rolling," shouted the director. "Idiot rolling," shouted I. And off I went, rolling hard and fast over the wet grass.

I picked up quite extraordinary speed and totally lost control. I eventually came to a stop in a crumpled heap at the bottom of the hill. I tried to stand up but I was too dizzy and I stumbled back over into a huge, hidden cow-pat. I got up again, and staggered out of shot.

Everyone clapped and started to pack up the equipment. I tried to look dignified as I pottered home soaking wet, bruised and covered in cow-shit. Note to self, next time you want to do "charidee" send them a cheque. It may bounce, but I won't, and it'll all be a lot easier.