“Then how could it leave the despatch-box?”

“I am not convinced that it ever did leave the despatch-box.”

“ Mr. Holmes, this joking is very ill-timed. You have my assurance that it left the box.”

“Have you examined the box since Tuesday morning?”

“No. It was not necessary.”

“You may conceivably have overlooked it.”

“Impossible, I say.”

“But I am not convinced of it. I have known such things to happen. I presume there are other papers there. Well, it may have got mixed with them.”

“It was on the top.”