I STOOD before the yawning mouth ready to swallow me up and sighed. This was no place for a man in his very early forties to be – a sentiment with which the lissom young semi-naked people surrounding me no doubt agreed.

Why did I agree to this, I thought? I don’t even like water slides. But sometimes a father has to do some awful and terrible things in order to assert his position as assistant to the head of the family. If I had wussed out of this, my charges would have been able to ride even rougher-shod over me than they normally do.

I am comfortable with playground slides – though no longer able legitimately to use them, as we established last week – but larger slides and I have a complicated history, dating back to the Llandudno Astroglide Incident of 1981.

For those of you who do not know what an Astroglide is – perhaps you were brought up Amish, or in a commune – it is a long, wide slide, separated into lanes, and which undulates from top to bottom. To ride upon the Astroglide, one must sit in a sort of sleeping-bag for masochistic hobbits.

The nine-year-old me was quite excited to be allowed on the Astroglide. I climbed into the mat and pushed off. I whizzed over the first hump, careered horizontally off the second hump, lost the mat mid-air on the way to the third hump, and rolled down the fourth, fifth, sixth and seventh humps.

I ended up in a traumatised, bruised heap at the bottom of the slide, and as I attempted to stagger away the boy who had launched himself after me arrived, at some speed, sweeping my legs from underneath me and sending me into a back flip which would have earned me an Olympic bronze had I landed on my feet, rather than my face.

In a way, it set up the abiding pattern of my life: anticipation, followed by early success, disappointment, humiliation and, finally, pain.

All this went through my head as I waited for the green light which would allow me to fling myself down the chute. The light flicked on and I pushed forward, noting as I went a sign which stated that the proprietors could not be held responsible for any damage caused to clothing by the slide.

What, I thought, as I slithered through the darkness. I thought the whole point of slides was that they were smooth. What sort of damage could be caused by a smooth slide? What sort of idiot designs a slide with…

Whoosh! My train of thought was derailed by the first big drop. I was picking up speed. This was going to be fun, I thought.

And then I emerged into the light. The flume was mostly outdoors. A gust of wind caught my chest, and I suddenly slowed. Wind resistance is the enemy, I realised. I lay on my back and sped up again.

“Ow!” I cried. “That really hurt.” My shoulder blades had scraped against a joint connecting one length of chute to the next, and in the process had slowed me down to a stop. I tried to push myself forward using the sides of the half-pipe but my hands could get no purchase. Apparently the least slippery part of the slide was the bit at the bottom. Or under the bottom.

And I couldn’t sit up. Every time I tried, I slipped back onto my back.

I could see there was another dip ahead, just around the corner. If I could get myself to that before the person behind me arrived, I would be all right. Somehow I managed to move myself to the corner, lying on my back, shuffling my backside – the only part of me able to adhere to the surface. I was relieved there was nobody there to see me. The humiliation would have been unbearable.

I inched around the corner. And there was a teenage girl, who had stopped herself and was, presumably, waiting for friends.

I tried to sit up but could not. All I could do was continue to edge forward, lying on my back, using my buttocks as my only means of propulsion, like a slug doing the backstroke. Her face showed the mixture of pity and disgust that only a teenage girl can display, and which I recognised from my own youth.

I managed to reach the dip before the next person arrived, but it was of little consolation.