“It’s a trap,” said Colin slowly. “I’m not going. You’ll damn well take my statement, whether you like it or not.”

“We’re not allowed to set traps, I promise you, I should be setting a trap if I pretended not to know which of you worked the lift and so encouraged you to carry on with your comedy of errors.”

“Do p-pipe down, Colin,” said Stephen rapidly. “It’s no go. I didn’t want you to do it. Mr. Alleyn, you’re quite right. I didn’t kill Uncle G. but, on my word of honour, I t-took him down in the lift and Colin stayed in the drawing-room. Don’t commit any more p-perjury, Col, for God’s sake, just go b-buzz off.”

The twins, white to the lips, stared at each other. It so chanced that each of them reflected the other’s pose to the very slant of their narrow heads. The impression made by identical twins is always startling to strangers. It is accompanied by a sensation of shifted focus. It seems to us that the physical resemblance must be an outward sign of mental unity. It is easy to believe that twins are aware of each other’s thoughts, difficult to imagine them in dissonance; and Alleyn wondered if these twins were in agreement when Colin suddenly said: “Let me stay here while you talk to Stephen, please. I’m sorry I was objectionable. I’d like to stay.”

Alleyn did not answer and Colin added: “I won’t butt in. I’d just be here, that’s all.”

“He knows everything about it,” Stephen said. “I t-told him.”

“If he first tells us what he did while you were in the lift,” said Alleyn, “he may stay.”

“Please do, Col,” said Stephen. “You’ll only make me look every kind of bloody skunk if you d-don’t.”

“All right,” said Colin, slowly. “I’ll explain.”

“That’s excellent,” said Alleyn. “Suppose you both sit down.”

They sat on opposite sides of the table, facing each other.

“I’d rather explain first of all,” Colin began, “that it’s not a new sort of stunt, our joining with the same story. It’s a kind of arrangement we’ve always had. When we were kids we fixed it up between us. I daresay it sounds pretty feeble-minded and sort of ‘ “I did it, sir!” said little Eric,’ but it doesn’t strike us like that. It’s just an arrangement. Not over everything but when there’s a really major row brewing. It doesn’t mean that I think Stephen bumped off Uncle G. I know he didn’t. He told me he didn’t. So I know.”

Colin said this with an air of stolid assurance. Stephen looked at him dully. “Well, I didn’t,” he said.

“I know. I was only explaining.”

“Later on,” said Alleyn, “we’ll look for something that sounds a little more like police-court evidence. In the meantime, what did you do?”

“Me?” asked Colin. “Oh, I just stayed in the drawing-room with Henry and my father.”

“What did you talk about?”

“I didn’t. I looked at a Punch.