I began to discard the lead weights from the belt, all the time sinking lower. By the time they had gone I was swallowed up to the waist. I tried to lean forward and swim like a flat fish on top of the stuff. No good. I returned or was returned to an upright position and seemed to stay there. I was not sinking any more, so long as I kept still, but I could never get out. I had checked the cylinders before the start and reckoned that I had about an hour more of life before the inevitable end. It made no difference whether I chose to die by drowning or by gradual disappearance into the sand.

I might last until the arrival of the bore. That must surely finish me since the sudden increase in depth would reduce my buoyancy still further. Mental arithmetic underwater had the most curious effect of increasing rather than reducing panic until I managed to get control of myself and was only madly impatient because I kept getting my simple sums wrong. Bottom of the ebb at the Guscar Rocks yesterday morning was 8.30, and today 10.10. This evening 11.00. But the bottom of the ebb here should be earlier than slack water down there. Hold on! That doesn’t matter to the bore. What matters is the Bristol Channel tide not the Severn, which, as I had seen, can ebb backwards if it likes. Bore passed the Guscar Rocks at 11.00. I had heard that its speed up-river was that of a galloping horse. Twelve miles it had to go. Say, fifty minutes. Bore due at 11.50. I should still have a little air left unless I had used up too much struggling with the fins. On the other hand, by standing still with sand up to my chest I was using a minimum. Not that it mattered. At 11.50, give or take ten minutes, I should be dead.

I think I could never have composed my thoughts if there had been a chance of life. I was as still as a post driven into the bed of the river. The water was comfortable, its temperature cold but not too cold, possibly due to fresh water coming down from sunlit meadows. So far as movement went I was already dead, or rather in the calm of dying with the familiar objects of vision all faded away. As best I could, being an agnostic, a hopeful agnostic, I tried to concentrate on the sort of ‘I’ which would be worthy to live without a body. The intellect, perhaps. The power to love, perhaps.

All colours darkened. The pressure on my ears was fierce and sudden. I cleared them, and then it seemed as if land and sea had dissolved into a chaos through which I was tossed and cartwheeled with no sense of position or up or down. I was conscious of speed and dreamed – so far as my brain worked at all – that it must be some limbo through which one passed at death. I never realised that the bore had passed over and taken me with it until I slammed hard into the entrance to a pill, the soft mud rising in a fountain of gobs as I hit it. The great wave, having sucked up the quicksand or forced its mass of water down into it, had carried me off along with the other debris in its path. Why I escaped I do not know. I should have gone roaring up-river, surfing on the crest like a log or a drowned cow, or been smashed to a sodden lump on the bottom. It may be that the weight and turbulence of water necessary to release me only operated a second or two after the crest had passed, or that my near-empty cylinders were heavy enough to hold me back.

Clawing like a cat in a flower bed, I reached a low branch of hawthorn and firm ground. Upstream the young moon seemed to show plumes of spray but that may have been due to mud on my mask or grass waving in the slipstream of air. The surface of the Severn was now quite even, with the tide running up behind the bore. I could imagine the silt settling, ready for the ebb to sweep it down again to the bottom of that still and deadly hole.

I did not know where I was, close to the Box Rock or a quarter of a mile up-river. The firm ground above the sharp mud valley of the pill turned out to be a little copse. I took off my harness and pushed through it, arriving at the riverside meadow where I had left my clothes. The bore had been merciful, lifting me and sweeping me round the rock.

At some time Marrin himself, while observing salmon or his soul, must have been nearly trapped in that deep chosen for my death. I don’t think that he had any such intention at the Guscar Rocks, though his readiness to take me along suggests that he needed to know how experienced I was and how I would react underwater in case later he should decide that I was a menace to – to what? I am still unsure. In every one of my theories there is a flaw.

My clothes were not where I had changed – he helping me, God damn him! I first assumed that Marrin had taken them back with him so as to leave no evidence. It then occurred to me that he might well require some false evidence and that he would have left my clothes on the bank in a likely place a good distance away. It would not be upstream because he would never have plunged across the pill. So it must be downstream and not far from some track, sure to be utterly deserted at night, where he had left his van. Would my clothes be in the open? Well, no. He wouldn’t want them to be easily discovered by the first passer-by next morning, but he wouldn’t mind if they were found accidentally or by a deliberate search later on, thus muddling the date when I actually disappeared. A fairly firm beach, where I might have been tempted to have an evening swim, would be a good place. It would then be assumed that I had been caught by some whirling backwash of the ebb and drowned.

My torch was still attached to me. I set off to walk along the bank, flashing it at intervals to see what was below: nothing at all but the swiftly rising Severn gliding past the mud. I came to the beginning of a sea-wall. A little way out was the top of a sandbank, which looked hard and was now separated from the land by a narrow channel and would have tempted any foolhardy innocent to go for a swim when the tide was low. It was easy to reach from a little beach of shale and mud immediately under the high bank, and not far away was a rutted farm track leading inland. I was sure this would have been his choice, but it took me the hell of a time to find the clothes in the dark. They were spread out above high-tide mark and hidden from the sea wall itself by waving long grass.

Clearly Marrin intended that my clothes and pack should eventually be found. It would not be known to whom they belonged, since nobody would report me as missing till I failed to come home from, supposedly, Spain. It was a hundred to one against the body ever turning up. If it did, caught in a salmon weir or bumping against a Gloucester lock, and was identified, the evidence of Broom Lodge would be straightforward. I had left in the afternoon. It was known that I was interested in tracing Roman ports. Yes, Marrin had lent me his diving kit. Yes, he had taken me out to the Guscar Rocks to be quite sure that I knew how to use it. The only snag was that I had not carried it when I left Broom Lodge.

I cannot guess how he intended to get out of that, unless he could persuade some members of the commune into a lie, or deny that the suit, which would be an unrecognisable rag, had ever belonged to him. But all this is guesswork. The more I think of it, the surer I am that he was dead certain that my body could never escape from the bed of the river and that the question would never arise. I presume he had satisfied himself before driving away from the colony to our rendezvous with the suits and aqualungs in the boot that I had said nothing to Elsa.

I was nearing the limit of endurance and could now rest and recover Elsa’s sandwiches from my pack with – thank God! – the strong Broom Lodge cider. I quickly changed and took that remote track across road and railway with my aqualung rolled in the suit and slung from a shoulder. I was shivering in spite of the fastest walk I could manage, and my only hope was to arrive soon at some quiet spot in the Forest where I could build a fire. I was instinctively against calling at the nearest house. For one thing it would have to be found; houses are few and far between on Severn banks. For another, Marrin was Elsa’s admired uncle. But I doubt if that would have counted if I had not been obsessed by gratitude for the sandwiches.