Two or three hours out of Camballin, in the course of which we never saw a living soul, nor knew for certain whether we were even on a track at all, having driven up and down mountains and along the beds of rivers, we suddenly came upon a road sign, a twisted arrow in a neat yellow triangle, warning us of an irregularity – to wit, a sharpish bend in the rubble. This was the equivalent of getting to within six inches of the summit of Everest and finding a notice alerting you to a steep incline just ahead. I consecrated this bizarre sign and the incongruous stony ground it stood on to ourselves and to our friend Philip Cochrane, a man of fastidious intellect whom we had first met at the West Country Trade Fair in Torquay where he had sold us fetching Liberty print purses to hang around the necks of little girls – thereby illustrating the truism, as we no doubt illustrated it for him, that you never know who or what you are going to meet where.

As witness what happened in Tunnel Creek, where our caravan finally came to rest at lunchtime, on the thirteenth tweet of Neil’s daytime watch precisely. An eroded limestone passage, open at either end but pitch black in the middle, Tunnel Creek was a popular spot for visitors when the roads were passable. Today we had it entirely to ourselves. A host of black butterflies, not expecting to be disturbed this early in the season, flew off the rock walls as we approached, darkening the air. Neil led us in, shining a torch so that we could see our way on what felt, beneath our feet, to be a mixture of rock and shingle. It was not unlike walking on a beach except that we weren’t out in the sunshine. It was a sickening place. Bats whistled and hung upside down above us. The frills and honeycombs of stone, sculpted by millions of years of dripping and seeping, were coated with a fine slime.

After a few minutes we saw water. According to Neil a virtual river flowed through here in the Wet, though now the water seemed still; as far as we could tell, merely a standing pool. Neil left us a torch so that we might gambol a little as we pleased, while he went back to prepare a gargantuan lunch for us and his computer to ingest.

We listened to him crunching back to the daylight. Then we were alone. Ros suggested a dip. I was against the idea. The tunnel made my flesh creep. What beauty it had was all of the sinister kind. Which was why the bats liked it.

‘No,’ I said.