We decided to find out what Marrin had been fishing for, on the off-chance that we might solve the problem of where he got his gold if he had not after all dug up a tomb. Taking the brake off too casually, the heavy dredge on the upper rope hurtled to the bottom while the revolving handle nearly knocked the major into the lake. At the same time the lower rope twirled fast and irregularly round the windlass. The lay-out was now plain. A single rope passed over the windlass and through a pulley placed – to judge by the angle – somewhere on the bottom inside the slit of the mouth. The dredge, attached to the upper rope, was lowered and pulled out tail foremost as far as the pulley. Then the revolution of the windlass was reversed; the dredge was dragged back in close contact with the bottom and kept from rising by some frame or hoop under which rope and dredge could pass. It could then be raised and emptied into a shallow hollow in the rock, where a little silt still remained, and the contents panned or strained. I suppose that after the catch had been examined the tailings were emptied into the flow on the other side of the cave with a bucket.

We put the windlass into operation, one of us on each handle, and it was hard work at that. The dredge brought up silt and fine gravel. No glint of gold or copper and no bones of glyptodont. Specks of iron and minerals unknown to me there were, including a few scraps of the same shiny black ore with which the furnace had been loaded and which I had heard was tin. I don’t know whether it could be smelted as it was, or whether it had first to be treated in Marrin’s laboratory. I am sure that when he set up his dredge, using suit and aqualung to fasten pulley and guide to the bottom, he hoped for gold – enough to give him cover for his real source. What he did find and recognised was cassiterite, the ore of tin: an unexpected and significant gift from Gwyn ap Nudd or his spirit deputy in charge of Wigpool.

We hung up the dredger exactly as we found it, and left at our ease for the entrance. It was shut. Only one of us could reach the underside of the pit props at a time, and it was impossible to move them. In case our voices could be heard outside, we retired down the gallery to the major’s former prison to discuss what we could do. There he seemed to have left behind him an atmosphere of tranquillity. Reasoning took over from panic.

‘They don’t know whether there is anybody down here or not, old boy,’ the major said, ‘because they haven’t looked. The pit props, now. Could have been removed by someone who had watched their comings and goings and was curious. Say, one of them goes by on some other business. Sees shaft is open. Won’t go in all alone. Closes up. Runs home to report. How’s that?’

It seemed unlikely. In that case we could expect the arrival in force of the regular churchgoers after dark.

‘We could stand where their entrance opens out into the gallery and bonk each one over the head as he appears,’ I suggested.

‘No right to use violence, Piers. Don’t know if they have any evil intent. Why should they have? We have done them no harm.’

I found it hard to believe that they would be so tolerant. After all, they had been lawless enough to kidnap the major, hide his car and shut him up just to make him confess why he did not believe that the burglar had taken the cauldron. It was probable that they had no more objection to violence than Marrin.

‘Or they may think I managed to move the pile of timber and escape,’ the major said.

I replied that they must know damn well that it was impossible, even if his strength was as the strength of ten, because his heart was pure. Clearly somebody else had unblocked the entrance and might or might not have persuaded him to leave.

‘But which somebody else? You?’

No, I said, not necessarily me. They had no reason to believe that I was anything but a friend of Marrin and a casual visitor to Broom Lodge, pretty certainly attracted by Elsa.

‘Splendid! Hadn’t remembered that! Then you can easily escape while I keep ’em occupied. That, Piers, is your duty to the Grail. Preserve it from them! You are unsuspected.’

‘If you can see any earthly way of escape it’s good for both of us,’ I replied.

‘Ha! I can! My story when I am detained will be that a person – I shall not mention his name, I’ll let ’em think there is a traitor among the faithful – came down to persuade me to leave. That, I am glad to say, is no lie. Two days ago you did. I refused to leave and he returned to the surface. A simple ruse de guerre. The enemy – if I may call them so – is advancing with no clear objective. I make him think that we are weaker than we are and his demonstration of force walks into trouble.’ He paused triumphantly. I was not impressed.

‘But where am I while you are being detained?’

‘You have swum out of sight under the lip of rock and will remain there until you can perhaps intervene.’

I objected that there could be no suprise intervention since I should be seen swimming back and that meanwhile I should have died of cold. However his idea could be improved. If I entered the mouth of the stream I could hide inside and watch developments. It was not a wide open recess so conspicuous that it invited exploration. They might not bother with it if the major’s story deceived them completely and made them sure he was alone.

‘To defend the approach, a long lance…’ he began.

‘Don’t forget the stirrups, Denzil! And I thought you had ruled out violence.’

‘In battle against the pagan, it is permissible not to turn the other cheek,’ he pronounced.

I doubted if the law would take that point of view. In a world less romantic than Arthur’s there was no reason why pagans should not call in the police; they were not committing any crime by opening up the old Wigpool workings and erecting an altar. The major and I were the aggressors who had interfered, or could easily be made to appear so.

We went back to have another look at the blocked entrance. No sound was to be heard outside. There was nothing to do but wait. It was not so chilly as in the forbidding depths, and faint strips of light coming through the pit props seemed to give us comforting but futile contact with the warm evening outside. I remember some snatches of empty conversation, and the major snoring and struggling with the infidels in his sleep, and an endless silence through which I myself may have dozed, for only one strip of light was left and that was grey. My watch said that it was after half-past eight, when I should have been at the rendezvous with Elsa. I hoped that she would not have appealed to the police. I tried to feel confident that we could deal with the four chief druidicals provided that there were no more of them and that they were not armed with bronze spears or bows and arrows.

‘And all for a quid’s worth of tin!’ I exclaimed.

‘Metals, Piers, metals To get their own. That was the point. And Wigpool an obvious choice.’

‘But which came first? Religion or metals?’

‘Both. You don’t understand ’em, old boy. Re-enacting the past for the sake of the future – you got that much. Think of the chap who first smelted a stone and found it poured out a liquid. Put it down to his gods, didn’t he? But you and I would say he had a bright idea or a lucky accident. Simeon believed that his bright ideas were inspired. You’ll admit he had some reason to. And he thought there was a something which inspired, same as the chap who put it down to the gods. Underwater, underground. Searching and worshipping. That was Simeon. It paid off if he really did find the cauldron in the Severn. Paid off here, too, from his point of view.’

He was silent for a moment shaking his head in the way he had, as if one self were rejecting the arguments of another self.

‘Visons of the past, old boy. Can’t explain them. Not reincarnation. It’s just that all time is one. You can’t get out of that if you believe in eternal life. I’ve had visions of the past myself. Can’t explain. Only last for a flash or two, but don’t know what world I’m in. Give you an example. When I was taking pictures of Simeon’s glyptodont, I knew at once that it was a pet. So bloody unlikely that I couldn’t have invented that for myself.’