‘Easy! Chap got in by climbing the drain pipe. Pipe passes within a couple of feet of the north window.’

‘But can you climb it?’

‘Of course I can. Always was good at P.T. But I’m not going to. I’m going down it.’

His plan was feasible. Having entered the lab from the estate office, he would open the north window and quietly smash the pane nearest to the catch (he knew about brown paper and treacle) so that the glass fell into the room. Then he proposed to mess up the room in true burglar fashion and break into the casket where the bowl was kept, grab it and leave by the drain pipe so that police or colonists could readily spot the marks of the burglar’s passage. He reckoned he could just about reach the pipe from the open window.

‘One snag,’ I told him. ‘You are leaving the door from the estate office unlocked.’

‘No, I’m not. When I’m safely on the ground, I can nip back to the estate office through the front door, lock the lab and shove the key back in the drawer. Great care all round. Wear gloves. Take cover when in doubt. Never hurry.’

‘Suppose someone pops out of a bedroom when you’re passing.’

‘Don’t care if he does. I’m on the way to have a piss. Some of ’em never waste it indoors. Good for the trees. May be right. Very sensible, some of their beliefs!’

I told him that he would have to take some gold trinkets as well as the cauldron to make the burglary appear convincing.

‘Yes, bothers me how we’re going to put them back,’ he said.

‘We don’t put them or the cauldron back till we have a quiet interview with him. He’ll talk, all right. Just seeing me alive will be enough to break him down.’

‘Suppose he really did make the bowl?’

‘Well if he did and has been buying gold on the market all along, we’ll be left with the problem of how the hell he makes enough profit to keep Broom Lodge running.’

For the major’s sake I hoped the burglary would succeed, but what excited me far more was that Marrin had loaded his diving kit into his van. I no longer had to keep an eye indefinitely on Bullo for him to appear, and then – if my patience lasted – to watch all night for his return.

I pointed out to the major that I could not take the cauldron up to London straightaway and that he would have to hide it for at least twenty-four hours while I rested – if that was necessary – and arranged the next move. I asked him to drive to Gloucester at once and to buy me a pair of fins at the best sports shop. Then he was to meet me at our usual place outside Drybrook at about quarter past nine and take me to Bullo, where Marrin kept his boat.

‘Didn’t know he had one!’

‘Well, he does. And wherever he goes he’ll have to wait for the turn of the tide to get back to Bullo; so you’ll have all night for the burglary and can take your time.’

All went according to plan. When he met me at Drybrook I curled up on the floor of the car, inconspicuous under the rug and the life jacket and slid out at the little lane to Bullo. Denzil was to drive on up-river and then make a detour to Broom Lodge so that there would be no chance of Marrin passing him on the road and recognising his car.

It was a warm, still evening, overcast, with not a sound but the lapping of the ebb against the stonework at the entrance to the pill. I lay down at the beginning of the avenue of hawthorn, where I could watch all movement on the banks. Marrin turned up about ten in the last of the light, on foot and carrying all his diving kit in a case made to fit, rather than my own untidy bundle. When he had gone down out of sight, I trotted along the avenue to the bank of the baby pill so that I could keep him in sight as long as possible. He was bound to set off downstream, for no little outboard motor could make way against the speed of the ebb.

All this while I had assumed that he meant to land at Arlingham and then walk along the bank until he arrived at his destination. I could not follow him, but I could intercept him on his return. But what good would that do unless he was actually carrying a gold bracelet or some other object from the hoard? I might not be able to bluff him into confessing where he had found it and I should lose all the advantage of being dead.

It was then that I had the wild idea of following him. I could come to no great harm so long as I stayed on or near the surface. I could never catch him up but I should not be far behind; and wherever he landed or anchored I should be able to make out the empty dinghy. Any success depended on his destination. The tide would carry him down the channel on the left bank for some three miles and then, swinging round the great bank of the Noose would take him back again for about the same distance to the right bank opposite Blakeney. I hardly dared to follow him as far as that through the twirlings and suckings of the yellow ebb, but on second thoughts I decided it would not be necessary. If his destination were on the right bank he had no reason to take a boat from Bullo; he had only to leave his car at any crossing of the railway, walk over the even Severn meadows and dive. Anyway that didn’t make sense. There could be no finding treasure under the mud.

It was far more likely that he intended to reach some point on the left bank without being carried round the Noose. Hock Cliff, which I had visited on the first day of my Severn ramblings, at once suggested itself. Unlike the red cliffs of the Severn, it was made of low lias clay and had been eaten back by the tides, leaving a flat terrace of rock at the edge of the shore. It was certainly easy to land there, but what for? However, leaving out the inexplicable diving equipment, Hock Cliff was a very possible site for treasure buried long ago on good, solid dry land well above the highest level of the river but now exposed by erosion. It was a theory which could be proved or disproved immediately.

I put on suit, life jacket, mask and aqualung and dropped into the mouth of the baby pill, being careful to keep my feet off the bottom. Marrin put-putted out of Bullo and passed close inshore, but could not possibly see me in the gathering darkness. I slipped out and followed, swimming well clear of the Box Rock, of which only a small part was showing above water. The dinghy was now far ahead of me, but occasionally I caught a glimpse of it when it bounced on the vicious wavelets of the ebb and the wake showed white. The sound of the engine told me that he was bound straight down-channel and not bearing a little to port as he would if he intended to land below Arlingham. I was about to give up and make for the Arlingham shore myself when the engine stopped and I thought I heard the splash of his heavy anchor; sound travelled half a mile over the sleeping Severn. So I kept on swimming until I could make out the dinghy anchored below the wood at the top of Hock Cliff. There seemed no reason why he should stop there. He still had his clothes on. I think now that he had arrived earlier than he intended and was waiting for the tide to fall a foot or two further. There turned out to be a handy little inlet in the rock terrace where the dinghy could safely lie when he left it, but he could not yet be sure of its position because the whole terrace was still awash, with the ebb dancing over it fast enough to hole or swamp the dinghy if he made a mistake.

I was in danger of being carried past him but managed to reach the edge of the terrace underwater and clung there by my fingers, as if I were a climber on a rock face, until I found a cleft which enabled me to relax and lift my head to watch the dinghy and Marrin. The ebb spat its silt at me and I remembered my agony in the quicksand. Then came disgust at the ceremony I had witnessed for the propitiation of my soul. Well, it wasn’t propitiated. Far from it! I was suddenly exasperated by all this folly – the silly side of them as Elsa had called it. Marrin, I had told the major, would break down as soon as he knew I was alive. And he’d break down worse still if he had a little additional evidence that I was dead.