‘Any more glyptodonts?’

A wild but just possible guess occurred to me.

‘No. But I may have found the pet’s collar.’

‘I think it was for a woman’s hair,’ she said, chipping away a crust. ‘The ends don’t meet.’

‘They don’t on a dog collar either.’

‘But they must have taken their wives on the ship.’

‘They took their wives and children to the highest ground and left them. And I’m not going back there to look for tiaras.’

Elsa shuddered. My description must have been vivid.

‘No! That horrible funnel!’

‘There’s just time to see if it comes to the surface,’ I said.

We left the dinghy and walked across the Stones to a point a little way back from the edge of the Shoots where a blowhole should appear if the cleft went right up through the rock. All the pools were motionless except one where the water and the floating weed pulsated up and down with an occasional spurt of foam.

It was now obvious to me why Marrin had never cleared the lot out at one go. Weight was the answer. He had no one to help him; he could never be dead sure of his time of arrival; and he would have found the same problem that I had – too heavy or too light and the fast tide ready to punish any miscalculation. So he decided to take no risks, leaving his treasure where it was and drawing on it in small quantities as required.

But I did have a helper. My determination never to dive again vanished. I had asked for trouble by arriving too late and staying too long. Provided I plunged in at the first sign of slack water and remained below for not more than ten minutes, there was little danger.

‘If we had some sort of smooth cylinder that won’t catch on the rock and lowered it down the blowhole at the end of a rope…’

‘You are not to, Piers. You said you wouldn’t.’

‘But this is easy. You at the top. Me at the bottom filling the cylinder. We can collect the lot in one dive, or two if the weight is too much.’

‘What are we to do with them?’

‘I don’t know. We’ll work it out. There are so many duties.’

The pools were filling now, and we had a longer and more devious walk back to our harbour, often with the rising tide rippling round our ankles. The dinghy was not there. I could see it a quarter of a mile away on its course for Gloucester.

It was my fault. I should have foreseen it. The dinghy was moored with the painter coiled round a large boulder at the far end of the inlet. Rendered half-witted by tiredness, excitement and the safe return to Elsa, I had never looked at the mooring when we walked off to find the pool. Meanwhile the rising tide had lifted the painter off the boulder.

Swimming was quicker than walking. I told Elsa to stay on a ridge of the Stones which would be the last to be covered, and struck out for the New Passage pill and Marrin’s rowing boat. It was where the ebb had left it, high above the water on a slope of mud, fortunately steep. I was nearly up to my waist in it before my feet touched a strip of gravel at the bottom of the stream and the boat slid into the water.

‘We’ll never catch up the dinghy,’ she said when I had rescued her.

‘No. But wherever the tide takes her, it ought to take us.’

She was no longer in sight, for it was after sunset. I rowed out to the point where I reckoned she would have been when we last saw her, shipped the oars and allowed the Severn to take over.

More embarrassment was to come. Evidently we had been watched for some time from the Welsh coast and when the dinghy was seen floating away we were taken for two very foolish tourists stranded on the Stones and in danger of drowning. A boat was racing out and came alongside.

‘That your dinghy what’s gone up river?’ the boatman asked.

The last thing we wanted was for him to chug up-river ahead of us, overtake the dinghy and find out what I had been diving for. How right Marrin had been to confine his explorations to the hours of darkness!

‘Don’t you bother!’ I said cheerfully. ‘We’ll catch her up in Slime Road.’

I think he was impressed that I knew the name of the main channel on the right bank.

‘If she don’t go up Oldbury and come to grief on the rocks. I wouldn’t bet on it. And what the goodness were ‘ee doing on the Stones with all that underwater rubber on ‘ee?’

‘Fishing,’ I answered and was searching for the least improbable lie when Elsa piped up in a sweet little-girl voice:

‘I wanted a swim and there wasn’t anywhere else.’

I took my cue and added apologetically, ‘You know what women are.’

‘Serve you right! Where you from?’

‘Chepstow. Came down on the tide.’

‘And that there boat?’

He couldn’t possibly have seen me take it out from New Passage.

‘Towing it, in case the girl wanted to go and bask on a sandbank.’

‘What she want to do that for?’

‘You see, I do love to sunbathe with nothing on,’ Elsa said.

The boatman must have been a good Welsh methodist, for he sheered off at once. If we were bound for hell anyway, it didn’t make much difference when we drowned.

‘Good night!’ Elsa called. ‘And thank you for wanting to help us.’

The fast flood had now swept us under Severn Bridge and into Slime Road, so it had probably done the same for the dinghy. She’d be pretty safe there, bumping her way up from soft bank to soft bank. The tide was not yet high enough for shipping to be proceeding up-channel. That was lucky. If the dinghy were picked up by some enterprising mariner and natural curiosity led him to see what was in the bag, we were not likely to hear any more of her – especially as my clothes were in the bottom indicating that the owner might have gone for a swim which was his last.

Twice we nosed into shore to examine possible dinghies; one turned out to be a stranded log and the other a drowned cow. We left it to the tide to do what it wished with us until we came to the tip of the Shepherdine Sands and had to make up our minds between the main channel and the Lydney channel. The boat, caught by a swirl, twisted round uncertainly three times until I back-watered and directed us, stern foremost, into the Lydney channel. Elsa, watching the wide and promising expanse of water the other side of the sands, protested. I replied that the dinghy might have been caught by a similar whirlpool and that we should put our trust in Nodens and the Roman Manual for pilots.

Neither let us down. The dinghy was aground, heeling over but still dry, just behind the Guscar Rocks, her ghostly helmsman trying to make the vanished port of Woolaston.

There was nothing we could do but wait alongside her for the tide to rise, and ensure that she remained on an even keel until she was on the shale beach where Marrin and I had come ashore from the rocks. It was after midnight and there was not a sound but the suckings and splashings of the river. The dim line of the railway embankment cut us off from the world.

Meanwhile, we discussed what should be done with the twenty or so pounds of gold which we had and the much larger quantity which remained in the cave.

‘What do you think happened to them?’ she asked.

‘All we know is that the tribes of the marshes did not know what gold was and had no use for it. My guess is that the adventurers never returned to the cave or the ship, and that the pet of the voyage died there.’

‘Perhaps they were taken away and worshipped like the gods which Uncle Simeon was training the colonists to be.’

‘Or made the common mistake of the half-civilised in taking a dance of welcome for a war dance and opening fire with whatever weapons they had.’

We moored the boats – safely this time – to a bush overhanging the bank, and slept a little in each other’s arms on the short, sheep-nibbled grass of a Severn lawn.

‘I could stay here for ever,’ she said.

An express from South Wales hurtled past on the embankment, the roar and the lights reminding us that we were not on a private planet of green earth and salt water orbiting the Milky Way overhead, but in a demanding modernity from which relief could only be obtained by labour on the land and by pretences, like those of Broom Lodge, that the world of machines did not or in the future would not exist.