At one minute after the quarter to seven I heard the rattle of the cans outside. I opened the front door, and there was my man, singling out my cans from a bunch he carried and whistling through his teeth. He jumped a bit at the sight of me.

“Come in here a moment,” I said. “I want a word with you.” And I led him into the dining-room.

“I reckon you’re a bit of a sportsman,” I said, “and I want you to do me a service. Lend me your cap and overall for ten minutes, and here’s a sovereign for you.”

His eyes opened at the sight of the gold, and he grinned broadly. “Wot’s the gyme?” he asked.

“A bet,” I said. “I haven’t time to explain, but to win it I’ve got to be a milkman for the next ten minutes. All you’ve got to do is to stay here till I come back. You’ll be a bit late, but nobody will complain, and you’ll have that quid for yourself.”

“Right-o!” he said cheerily. “I ain’t the man to spoil a bit of sport. Here’s the rig, guv’nor.”