‘Either,’ Fox said stolidly, ‘he was coshed by a left-handed person standing behind him or by a right-handed person standing in front of him and at least three feet away.’

‘Which would place the assailant,’ said Alleyn, ‘about twelve inches out on the surface of the stream. Which is not as absurd as it sounds when you put it that way. All right. Let’s move on. What comes next?’

The Chief Constable who had listened to all this in silence now said: ‘I gather there’s a cry of possible witnesses waiting for you at Hammer. That’s Cartarette’s house up here on Watt’s Hill. If you’ll forgive me, Alleyn, I won’t go up with you. Serve no useful purpose. If you want me I’m five miles away at Tourets. Anything I can do, delighted, but sure you’d rather be left in peace. I would in my day. By the way, I’ve told them at the Boy and Donkey that you’ll probably want beds for what’s left of the night. You’ll find a room at the head of the stairs. They’ll give you an early breakfast if you leave a note. Goodnight.’

He was gone before Alleyn could thank him.

With the sergeant as guide, Alleyn and Fox prepared to set out for Hammer. Alleyn had succeeded in persuading the spaniel Skip to accept them and after one or two false starts and whimperings, he followed at their heels. They used torches in order to make their way with as little blundering as possible through the grove. Oliphant, who was in the lead, suddenly uttered a violent oath.

‘What is it?’ Alleyn asked, startled.

‘Gawd!’ Oliphant said. ‘I thought someone was looking at me. Gawd, d’you see that!’

His wavering torchlight flickered on wet willow leaves. A pair of luminous discs stared out at them from the level of a short man’s eyes.

‘Touches of surrealism,’ Alleyn muttered. ‘In Bottom Meadow.’ He advanced his own torch and they saw a pair of spectacles caught up in a broken twig.

‘We’ll pluck this fruit with grateful care,’ he said, and gathered the spectacles into his handkerchief.

The moon now shone on Bottom Meadow, turning the bridge and the inky shadow it cast over the broken-down boat shed and punt into a subject for a wood engraving. A group of tall reeds showed up romantically in its light and the Chyne took on an air of enchantment.