Too late now. At the top of the slope I stripped off my clothes and left them in a heap on top of my shoes. Then, with the head-lamp back on and the bolt-cutters in my right hand, I waded into the black flood.

The water was cold as ice. I gasped as it reached my crotch, but strode forward hard in an attempt to keep my blood moving. Quickly my whole body became submersed. I made paddling movements with my hands to speed my progress. Soon I was up to my neck, then up to my chin. Down came the roof, down, down. I reached the point at which, with the top of my head touching the bricks, my mouth was under water and my nose just entering it. From now on the only way I could breathe was by tilting my head back and turning my face upwards in the narrow airspace. To do that I had to push the headlamp on to the back of my head so that it didn’t foul the roof.

I took a deep breath, ducked under and drove forward, five steps, ten. Desperate for oxygen, I came up in that peculiar attitude, hit the roof with the headlamp, pushed it back, gasped in a breath and inadvertently got half a mouthful of filthy liquid. When I choked explosively, all the grot flew upwards and came back down in my face. The setback left me gasping. For a few seconds I fought panic. Keep still! I told myself. Get yourself together.

With my mouth shut, I took in some air through my nose. Then to my dismay I realised that in going for the headlamp I’d dropped the shears. I felt around with my bare feet. No contact. Had I moved forward a short distance while struggling for air? I shuffled back a few inches and felt around again. Still nothing.

The cold was getting to me. I could feel my legs starting to go numb. If you piss about here any longer, you’re going to get cramp and bloody drown yourself, I thought. Leave the damned things. You can manage without them.

I waded on. Then, after one more stop for air, the water level began to drop. My head came clear: once again I could walk and breathe normally.