“Very good, Dr. Markfield. We'll stick to facts, if you like. Now once upon a time you saw Dr. Silverdale acting in some private theatricals, I believe. I learned that from Dr. Ringwood. That's correct, isn't it?”

“Yes. We were members of a small amateur show at one time.”

“In any of his parts, did Dr. Silverdale play the banjo?”

Markfield reflected for a moment.

“I think he did.”

“He's an expert banjo-player?”

“He plays the banjo,” Markfield corrected. “I'm not going to give you my opinion about his playing. That's not a question of fact; it's a mere matter of taste.”

Flamborough let this pass without comment.

“He plays the banjo, anyhow. That's what I want to get at.”

He stepped across the laboratory to where a little glass apparatus was attached to a tap at a sink and examined the rubber tubing attached.