Dr Elekton came back. ‘It’s the paper-weight sure enough,’ he said. ‘Trace of blood on the edge.’ He went to the sofa and took Mr Period’s hand in his.

‘Don’t worry,’ he said. ‘You’re all right.’

The flaccid lips parted. After an indeterminate noise a whisper drifted through them: ‘It was that song.’

‘Song? What song?’

‘He’s deeply concussed, Alleyn.’

‘What song?’

‘Should have told Alleyn. Whistling. Such awfully bad form. Luncheon.’

‘What song?’

‘Couldn’t – out of my head,’ Mr Period whispered plaintively. ‘So silly. “Okay by me”. So, of course. Recognized. At once.’ The sound faded and for a moment or two the lips remained parted. Then Mr Period’s voice uncannily articulate said quite clearly: ‘May I speak to Superintendent Alleyn?’

‘Yes,’ Alleyn said, holding up a warning hand. ‘Alleyn speaking.’

‘Just to tell you. Whistling. Recognized it. Last night. In the lane. Very wrong of me not to – Divided loyalties’ There was a longish silence. Alleyn and Elekton stared absently at each other. ‘“Okay by me”,’ the voice sighed. ‘So vulgar.’

The eyes closed again.

‘This may go on for hours, Alleyn.’

‘How much will he remember, when he comes round?’

‘Everything probably, up to the moment he was knocked out. Unless there’s a serious injury to the brain.’ Dr Elekton was stooping over his patient. ‘Still bleeding a bit. I’ll have to put in a couple of stitches. Where’s my bag?’ He went out. Fox was talking to the men in the hall. ‘We’ll seal the library and cover the area outside the window.’

‘Do we search?’ asked somebody. Williams, Alleyn decided.

‘Better talk to the chief.’

Fox and Williams came in with Dr Elekton who opened his professional bag.

‘Just steady his head, will you?’ he asked Alleyn.

Holding Mr Period’s head between his hands, Alleyn said to Fox and Williams: ‘It looks as if the thing was thrown at him by somebody standing between the table and the French windows while he was ringing me up. I heard the receiver knock against the desk as it fell and I heard a click that might well have been made by the windows being pulled to. You’re not likely to find anything on the drive. It’s as dry as a bone and in any case the French doors are probably used continually. Whoever made the attack, had time to effect a clean getaway before we came trundling in, but I think the best line we can take is to keep watch in case he’s still hiding in the garden – Raikes and Thompson can do that – and Fox, you rouse up Miss Cartell’s household. Somebody will have to stay here in case he speaks again. Bob, would you do that?’

‘Right,’ said Superintendent Williams.

‘I’ve got a call to London.’

To London?’ Williams ejaculated.

‘It may give us a line. Fox, I’ll join you at Miss Cartell’s. Okay?’