With the slow march of a priestess, Elsa in her black robe, the cauldron held with both white arms above her head, walked towards the altar. She was as beautiful and timeless as some worshipper from the walls of an Egyptian tomb bringing an offering to Isis.

If their astonishment had not been so manifest I would have thought they had been waiting for her. Better theory: that she was returning the bowl in the hope that if they were holding us they would release us. Impulsive, crazy rescue. Could end disastrously on that altar. What an unparalleled sacrifice of the beauty of the world! All this went through my mind in a second, followed by a savage inspiration direct from Gwyn ap Nudd himself or at least worthy of him. Evans had backed against the windlass, one robed arm gripping the structure. I crawled quickly behind him, reached up and released the brake.

What I intended – and I swear that was all – was that the handle of the winch should knock him into the water and give us a chance to escape in the confusion. The lower rope came in while the upper rope attached to the heavy dredge whooshed out across the lake. Evans went with it, the flared sleeve of his robe caught in the dredge and possibly his arm as well. He kicked and yelled, but there he hung until he splashed into the black mirror and disappeared into that grinning opening between rock and water where the lake continued on to the unknown.

I kept low. Nobody had seen me. Two of them threw off their robes and swam out. A third man ran for the windlass and struggled with the looping rope and the brake. After that he was fully occupied, for I had reached out for the torch he had dropped and set his nightdress on fire.

I yelled to Elsa to run, for she was nearest to the passage. That brought our dreaming Perceval to life. He launched himself from his knees with the dash of the cavalry, butted Raeburn in the wind, doubled him up and raced on to cover Elsa’s retreat. Only two of the congregation, who had been helplessly watching the swimmers, were ready for action. By the time that I had jumped up to dry land and was running for the passage, they were almost on me but slowed down by their robes and their torches.

Elsa and Denzil were struggling along in the dark until I was near enough for the beam of my flashlight to show them the way. Together we splashed through the pool and round the buttress of rock, so that our pursuers were momentarily out of sight but far too close for comfort. It occurred to me that when the three of us were scrambling out through the entrance, necessarily in single file, the last one would be caught. So I handed my light to the major and snapped at him to get clear with Elsa and the cauldron, for I knew the way and would be in no danger.

There could be no question of defending the passage without a weapon; they could deal with me by shoving a torch in my face. But what gave me confidence was the patchy light of those torches, showering red smoke and sparks as they ran and illuminating the roof and sides of the gallery without throwing any beam ahead. I let them come round the buttress before I shot off, so giving Elsa and Denzil a good start of some seconds. As I expected, escape was not too difficult. They could see nothing twenty yards ahead of them while I was in a pink, faint dusk just sufficient to prevent me tripping over any obstacle.

But my brilliant idea turned out disastrously. As I swung round into the straight lateral gallery I saw Denzil’s light vanish round the bend far ahead of me – too far ahead of me. The pair had gone straight on, passing Marrin’s entrance, and had turned into the blocked shaft. I should have foreseen that that could happen. The major, unconscious when he was brought in, had no picture at all of his whereabouts, and Elsa in her rash, passionate attempt to get through and deliver up the cauldron had never glanced back to see what the entrance looked like from below.

The temptation was to follow my love whatever happened; it was too late to shout to them to turn back. Commonsense somehow overcame emotion. If I could get out and summon help, it would not be long before the pair of them were free. So I turned right and plunged at the correct entrance with one of my followers so close behind me, owing to my momentary hesitation, that I felt him grab at my ankle as I crawled through. Once clear of the pit props, I sprinted and dropped into cover. No nonsense of bonking my pursuer on the head. I had done too much damage already for easy explanation in court.

It was the converted boxer who emerged. He relit his torch and had a look round above and below the slope but never spotted me among the tussocky grass. Only when he had returned below did I realise that they would assume all three of us had escaped, not just the mysterious unknown who released brakes and set fire to surplices. With sight limited by the wavering red circle of the torches they could not possibly have judged how far ahead was Denzil’s light when it disappeared, if indeed they had noticed it at all.

That encouraged me to attempt some immediate tactical surprise rather than to wander off to scattered cottages and try to raise a posse among unbelieving villagers. Provided that I could return unseen, and provided that it was at all possible to get a picture of the movements and intentions of these scurrying and disorganised moles, I ought to be able to create a diversion. So I returned, wriggling like a snake into its hole and praying that no sound of displaced stone or pit prop would give the movement away.

By this time I was very familiar with the plan of the galleries. It was simple – much like the letter F with a tail. The small bar was the druidicals’ entrance and the long bar the original adit, now blocked, where Elsa and the major would be silently crouching and wondering what the devil had happened. At the bottom of the F the gallery curved away downhill until it ended at the pool. I waited at the junction of the small bar and soon heard the low voices of two or perhaps three in the gallery to my right. It was the most awkward place they could have chosen. There was no hope of reaching Elsa and the major till these people were moved: I don’t know why they had chosen the place – certainly to be at hand in case the fugitives started to put back the pit props, possibly to be able to rush out from the dark directly behind anyone who returned as I had done. They had extinguished their torches.

I felt my way along the cut-rock wall, round the corner at the tail of the F and down the passage to see if there was any earthly chance of decoying them away. I could of course hear nothing at all from the direction of the cavern and had to take the gamble that they were all occupied with the rescue of Evans. He would not be very deep down and it would not be difficult to cut him free if one of the fools had a knife and if it were only the robe which was caught. But after that would come the longer business of resuscitation.

I felt oppressed and defenceless in the absolute darkness, and noticed that I was trembling. What scared me was that a party might come up, bearing Evans, and that I should be trapped between them and the picket at the entrance. I suppose that imagined fears are often worse than real danger – which God knows I had been in down below and had not time to think about.

Half way down the gallery my misgivings were justified. I heard splashings as feet passed through the pool. The only possible hiding place was the major’s home from home, and I slipped inside the recess till the footsteps of one man had safely passed.

When all was quiet I struck some matches and ventured a quick look round. It was the changing room. The major and I had seen little sign of it since no solemn ceremony was then going on. There were seven silly little flat cases in which the celebrants had brought their robes. On hangers were three coats and a spare robe. Two spare torches were leaning against the wall beneath them. The oil lamp had been put out.