For a second or two Alleyn wondered if there would be an explosion or, worse, a retreat into heavy silence. Fearing that the expression of gloating delight upon Harper’s face might turn the scales, Alleyn had placed himself between the chief constable and his superintendent. But Colonel Brammington behaved admirably. He goggled for a moment, he became rather more purple in the face, and he made a convulsive movement that caused his shirt-front to crackle sharply, but finally he spoke with composure.

‘Your manners, my dear Alleyn,’ he said, ‘are, as always, worthy of a Chesterfield. I am pinked on the very point of a compliment. The wrong man? Indeed? Then I must be ludicrously at fault. I have made some Gargantuan error. My entire sequence of deductions—’

‘No, no, sir. Your case against Parish is supported by facts, but not by all the facts. Parish might so nearly have murdered Watchman, by either of the two methods you’ve described.’

‘Then—Well?’

‘The circumstance that excludes Parish, excluded his only means of murder. If he did it, it was by poisoning the brandy, and he couldn’t tell which glass would be used. Not possibly. But we’ll come to that in a minute. Our case, and I’m afraid it’s a dubious one at the moment, is that there are one or two scraps of evidence that only fit into the pattern if they are allowed to point in one direction, and that is not towards Parish.’

‘What are they? More beer, I implore you.’

‘To begin with,’ said Alleyn, filling Colonel Brammington’s glass, ‘the two iodine bottles.’

‘What!’

‘Shall we take them, sir, as they turn up?’

‘Let us, for God’s sake.’