Dunwiddy was a round ball of a man with a fitting rotundity of wit and wisdom. He made me wait some time, but, as soon as he had opened his office door and set eyes on me, received me with a cordiality for which I could not account.

He led me to talk of my interest in ancient economies and thus, via agriculture in the Forest of Dean, eased the way to my impressions of Broom Lodge.

‘I trust, Mr Colet, that the commune will now farm the hereditament with enterprise and without enthusiasm.’

Catching his obscure meaning, I replied that I did not think belief in reincarnation ever had much effect on their efforts to make the place pay.

‘Indeed I myself do not order my day to conform with the cathedral chimes, except that I go home at compline when they, I understand, exchange the plough for meditation and the ministrations of the admirable Elsa. By the way can you tell me where she is?’

‘I don’t know. I understand she left very suddenly.’

‘Come, come, Mr Colet! There was a day when local business compelled me to take luncheon in Thornbury. It so happened that I saw Adam and Eve – fully clothed, I assure you – walking in the garden. I am old but not old-fashioned. And as an experienced solicitor I recognise a distinction between love in the eyes and eying with love. I hope that for your sake and hers you are only observing a gentlemanly discretion when you tell me that you do not know where she is.’

I allowed him to think so and said that in fact she had gone to stay with my mother.

‘Excellent! Excellent! Would you be good enough to let her know that I am anxious to see her?’

‘Of course. Can I help at all?’

‘I doubt it. No one ever can. It is a question of a car which presumably should be included in Mr Marrin’s estate. The boat which contributed to his sad end is obviously the property of the commune, though an unpleasant, puritan sort of fellow named Evans with whom I had a preliminary talk knew nothing about it. The car, now. A good lady at Bullo is sure that he sometimes crossed the river at night and returned before dawn. The police have made enquiries whether anything was known – let us say of a secret liaison – at Overton or Arlingham. Nothing. And you will agree, Mr Colet, that in small villages scandal, often amounting to criminal slander, is the breath of life. So the police were sure that Mr Marrin’s business was further afield and that he must have had a car at his disposal. They found it. He kept it in an outlying barn which he had rented at Fretherne – a remarkably quiet hamlet just above Hock Cliff. It was a grey Morris, inconspicuous at night as a grey rabbit. So, it appears was he. It’s quite extraordinary how so commanding, unforgettable a man could drift out of Broom Lodge leaving no more trace behind him than a ghost – in the existence of which, as he once informed me when I was engaged on a breach of tenancy due to persistent haunting, he firmly believed.’

I could not help Mr Dunwiddy, but he had helped me. I had never thought of a car permanently garaged on the left bank within easy reach of Marrin’s landing place. All I knew – and that I kept to myself – was that he set out on a falling tide which would carry him over the river to the Hock Cliff. He had then only to wait for the flood to carry him back again to Bullo. What did he do meanwhile?

After I left the solicitor’s office I decided to cover again, this time by car, all the left bank of the Severn where I had walked and waded in search of an unknown Roman port. My theory of a treasure – of Nodens, as I had called it – which Marrin had dug up was not demolished at all; only the cauldron was. Without doubt it was modern and he had made it, but of pure gold which, according to the Museum, no craftsman, ancient or modern, would use.

The site must be too far from Hock Cliff to walk. That stood to reason, anyway. Before the desolate stretches of sea wall were built, the river plain on the left bank was flooded at high tide and must have been a network of mud and marsh at low. So the bank itself could be eliminated as fit for a burial mound or temple treasury, as well as the miles of meadow intersected by pills which even today could overflow when a spring tide came up with a south-west wind behind it. Where did he go in that inconspicuous Morris? Between dusk and dawn he had time enough to reach far into the Cotswolds, dig and return.

The devil! In all this line of speculation I had forgotten that Marrin’s case with all his diving equipment was in the dinghy. So it had to be the Severn and nowhere else. And he would dive from the bank as he always did, not from an unstable boat. But why not take the boat all the way to the chosen site? Answer simple. If he went down on the tide beyond Hock Cliff and the Noose he would never be nearer to the left bank than the mud flats.

I wasted two days on the job, spending the nights at Gloucester. An utterly frustrating period with grey clouds spitting drizzle at me above, and Severn mud over my boots below. In the back of the car was all my equipment for diving, but I had no need to unpack it. I ruled out the sandbanks and the shoals which could never be excavated by a single-handed diver. I ruled out the low red cliffs of marl and sandstone constantly eaten away by the torrents of the ebb to form beaches. I ruled out pills and meadows. In all the centuries from the bronze age onwards no one would ever have buried a chieftain or built a temple where the next spring tide would turn the site to marsh and a year later to a mudbank separating two new channels. So I gave up and returned to London and Elsa.

I had called her up every evening and gathered that she was happy window-shopping, sightseeing and appreciating a solitary holiday in my flat after the insistent group society of Broom Lodge. I found her more delicious than ever. The abbess had fallen away along with her robes and there she was on the wings of womanhood, lovely, intelligent, irreverent and spreading round her an infectious delight in being alive.

On the second day, when we came home from celebrating our reunion by a lunch far too joyously expensive for a second-rate historian of ancient economies, the telephone was ringing and she jumped to it – for in my experience no woman will ever let an insistent telephone alone – though the call had to be for me. But it wasn’t.

‘It’s the major for me,’ she said, her hand over the mouthpiece, and carried on a conversation of which I could make little at her end. She too looked puzzled.

‘He says that all of them need me, and there’s no risk from the half-wits. I’m holy or something.’

‘That’s what he said about himself.’

They are running short of cash, he says, and we should return Uncle Simeon’s brooches and ash trays and things. What does he mean?’

The major had clean forgotten that we had never told Elsa that he was the burglar. Now that had to come out.

She listened to my story disapprovingly. ‘But I still don’t see why he did it,’ she said.

‘For the sake of his old friend. I should never have agreed, but I did. You see, he didn’t believe in the alchemy for a moment. He was afraid that your uncle was stealing gold somewhere or that he was faking antiquities to sell them as genuine finds. I suspected – and I still do – that he had really found a buried hoard and was breaking it up. Iniquitous! So we determined to get hold of the cauldron for a couple of days so that I could take it to the British Museum. But Denzil was always halfway to believing it might be the Grail and his nerve failed him. He wouldn’t lay hands on it. So he left it and just emptied out the drawer of trinkets. That’s what we have to return.’

‘Denzil Matravers-bloody-Drummond behaved like a two-year-old,’ she exclaimed, ‘and you too. And then you have to carry out this crazy plan on the night Uncle Simeon was drowned!’

‘We didn’t know he was going to be drowned,’ I said weakly.