‘That’s right. An amateur. Do you find it a sinister hobby? It has rather a sinister reputation, I fear. There was that terrifying film and then didn’t somebody in The Hound of the Baskervilles flit about Dartmoor with a deceiving net and killing-bottle?’

‘There’s Nabokov on the credit side.’

‘True. But you don’t fancy it, all the same,’ he said. ‘That I can see, very clearly.’

‘I like them better alive and on the wing. Did you notice those two motorcyclists? They seem to be haunting us.’

‘Friends of young Tom, it appears. They come from Tollardwark where we stay tonight. Did you know it’s pronounced Toll’ark? It will take us an hour or more to get there by water but by road it’s only a short walk from Ramsdyke. There’s confusion for you!’

‘I wouldn’t want to walk: I’ve settled into the River-time-space-dimension.’

‘Yes, I suppose it would be rather spoiling to break out of it. Hallo, that’ll be for us.’

The Zodiac had given three short hoots. They returned hurriedly and found her waiting downstream from the lock.

There was a weir at Ramsdyke, standing off on their port side. Below the green slide of the fall, the whole surface of the river was smothered in foam: foam in islands and in pinnacles, iridescent foam that twinkled and glinted in the late afternoon sunlight, that shredded away from its own crests, floated like gossamer and broke into nothing.

‘Oh!’ cried Miss Rickerby-Carrick in ecstasy. ‘Isn’t it lovely! Oh, do look! Look, look, look!’ she insisted, first to one and then to another of her fellow-passengers. ‘Who would have thought our quiet old river could froth up and behave like a fairytale? Like a dream isn’t it? Isn’t it?’

‘More like washing-day I’m afraid, Miss Rickerby-Carrick,’ said Mrs Tretheway looking over the half-door. ‘It’s detergent. There’s a factory beyond those trees. Tea is ready in the saloon,’ she added.

‘Oh, no!’ Miss Rickerby-Carrick lamented. A flying wisp of detergent settled on her nose. ‘Oh, dear!’ she said crossly and went down to the saloon, followed by the others.

‘How true it is,’ Caley Bard remarked, ‘that beauty is in the Eye of the Beholder.’

He spoke to Troy but Dr Natouche, who was behind her, answered him.

‘Surely,’ Dr Natouche said, ‘not so much in the eye as in the mind. I remember that on a walk—through a wood, you know—I looked into a dell and saw, deep down, an astonishing spot of scarlet. I thought: Ah! A superb fungus secretly devouring the earth and the air. You know? One of those savage fungi that one thinks of as devils? I went down to look more closely at it and found it was a discarded fish-tin with a red label. Was it the less beautiful for my discovery?’