“Kemp could have seen the library window if he had stood here,” he said.  “I should say that if the blind were up it would be possible to see right into the room.”

“What do you say, Chippenfield?” asked Crewe, turning to that officer.

Inspector Chippenfield had taken his stand stolidly on the centre path of the Italian garden, directly in front of the window of the library.

“I say Kemp is a liar,” he replied, knocking the ash off his cigar.  “A d——­d liar,” he added emphatically.  “I don’t believe he was here at all that night.”

“But if he was here, do you think he saw Sir Horace leaning out of the window?”

“I don’t see what was to prevent him,” was the reply.  “But my point is that he was a liar and that he wasn’t here at all.”

“And you, Rolfe—­do you think Kemp could have seen Sir Horace leaning out of the window if he had been here?”

“I should say so,” remarked Rolfe, in a somewhat puzzled tone.

“I am sorry I cannot agree with either of you,” said Crewe.  “I think Kemp was here, but I am sure he couldn’t have seen Sir Horace from the window.  Kemp has been up here during the past few days in order to prepare his evidence, and he’s been led astray by a very simple mistake.  If a man were to lean outside the library window now there would not be much difficulty in identifying him, but when the murder took place it would have been impossible to see him from any part of the garden or grounds.”

“Why?” demanded Inspector Chippenfield.

“Because it was the middle of summer when Sir Horace Fewbanks was murdered.  At that time that chestnut-tree would be in full leaf, and the foliage would hide the window completely.  Look at the number of branches the tree has!  They stretch all over the window and even round the corners of that unfinished brickwork on the first floor by the side of the library window.  A man could no more see through that tree in summer time than he could see through a stone wall.”

“What did I tell you?” exclaimed Inspector Chippenfield in the voice of a man whose case had been fully proved.  “Didn’t I say Kemp was a liar?  We’ll call evidence in rebuttal to prove that he is a liar—­that he couldn’t have seen the window.  And after Holymead is convicted I’ll see if I cannot get a warrant out for Kemp for perjury.”

“And yet Kemp did see Sir Horace that night,” said Crewe quietly.

“How do you know?  What makes you say that?” The inspector was unpleasantly startled by Crewe’s contention.

“He was able to describe accurately how Sir Horace was dressed—­for one thing,” responded Crewe.

“He might have got that from Seldon’s evidence,” said Inspector Chippenfield thoughtfully.  “He may have had some one in court to tell him what Seldon said.”

“You do not think Lethbridge would be a party to such tactics?” said Crewe.  “No, no.  One could tell from the way he examined Seldon and Kemp on the point that it was in his brief.”