‘I think so. I explained to Harper this afternoon that I thought it better not to make an arrest at once. We realized that our case rested on a few facts and a mass of dubious conjecture. Fox and I pretend to despise conjecture, and we hoped to collect many more bits of evidence before we fired point-blank. We still hope to get them before Legge comes up for assault and battery. We hope, in a word, to turn conjecture into fact. Until this evening I also hoped to get more from Legge himself, and, by George, I nearly got a dose of prussic acid. He must have slipped into the taproom and put his last drop of poison in the decanter. He must also have had that last drop hidden away in a bottle somewhere ever since he murdered Watchman. Not on his person, for he was searched, and not in his room. Perhaps in his new room at Illington, perhaps in a cache somewhere outside the pub. Some time after Harper had searched his room, Legge got rid of a small glass dropper with a rubber top. If he used it to draw prussic acid from the rat-hole, he must have cleaned it and filled it with his lotion, emptied it and restored it to its place on his dressing-table. If he also used it to do his work with the decanter, he got rid of it this afternoon together with whatever vessel housed the teaspoonful of prussic acid. We’ll search for them both.’

Alleyn paused and looked round the circle of attentive faces. He raised a long finger.

‘If we could find so much as the rubber top of that dropper,’ he said, ‘hidden away in some unlikely spot, then it would be goodbye conjecture and welcome fact.’

III

‘A needle,’ cried Colonel Brammington after a long pause, ‘a needle in a haystack of gigantic proportions.’

‘It’s not quite so bad as that. It rained pretty heavily during the lunch-hour. Legge hasn’t changed his shoes and he hasn’t been out in them. They’re slightly stained and damp. He crossed the yard several times, but he didn’t get off cobble stones. The paths and roads outside the pub are muddy. He’s therefore either thrown the bottle and dropper from the window or got rid of them in the house or garage.’

‘Lavatory,’ said Fox gloomily.