‘That doesn’t help since he was killed before the rain and found before the rain. But consider, Brer Fox, he was killed with a tuft of cut grass in his hand. Isn’t it at least possible that he was cutting his grass to wrap up his own catch? He had refused to touch the Old ’Un and had left it lying on the bridge. The people who knew him best all agree he’d stick to his word. All right. Somebody kills him. Is it that “somebody” who takes the Colonel’s fish and replaces it with the Old ’Un?’

‘You’d think so, Mr Alleyn, wouldn’t you?’

‘And why did he do it?’

‘Gawd knows!’ said Oliphant in disgust. Sergeants Bailey and Thompson and PC Gripper made sympathetic noises. Dr Curtis, squatting by the stretcher, grinned to himself.

‘What was the actual position of the killer at the time of the blow or blows?’ Alleyn continued. ‘As I read it, and you’ll correct me here, Curtis, Colonel Cartarette was squatting on his heels facing the stream with the cut grass in his hands. The heel marks and subsequent position suggest that when he was struck on the left temple he keeled over, away from the blow, and fell in the position in which Nurse Kettle found him. Now, he was either belted from behind by a left-hander or rammed by a sort of crouching charge from his left side or struck from the front by a swinging right-handed swipe … Yes, Oliphant?’

Sergeant Oliphant said: ‘Well, pardon me, sir, I was only going to remark would it be, for example, something like the sort of blow a quarryman gives a wedge that is sticking out from a rock-face at the level of his knee?’

‘Ah!’ said PC Gripper appreciatively. ‘Or an underhand serve, like tennis.’

‘That kind of thing,’ Alleyn said, exchanging a look with Fox. ‘Now there wasn’t enough room between the Colonel and the brink for such a blow to be delivered: which is why I suggested his assailant would have had to be three feet out on the surface of the stream. Now, take a look upstream towards the bridge, Brer Fox. Go roundabout, because we’ll still keep the immediate vicinity unmucked up, and then come out here.’

Fox joined Alleyn on the lower bank of the little bay at the point where it jutted farthest out into the stream. They looked up the Chyne past the willow grove, which hid the near end of the bridge, to the far end which was just visible about forty feet away with the old punt moored in the hole beneath it.

Alleyn said: ‘Charming, isn’t it? Like a lead pencil vignette in a Victorian album. I wonder if Lady Lacklander ever sketches from this point. Have you read The Rape of Lucrece, Brer Fox?’