"About twenty-five."

"And Lady Leconbridge?"

"Two or three years older."

"And Mr. Lester's support of Lady Leconbridge when she preferred the pearls only made his father more determined that the diamonds should be worn. I wonder----"

"Ah! that past gossip is having its effect upon your judgment," said Quarles.

"You may put that idea out of your mind, Zena," I said. "Mr. Rupert Lester is engaged to Miss Margery Dinneford. It is common knowledge that old Dinneford had other views for his only daughter, but finally allowed his opposition to be overruled. Margery Dinneford and Lady Leconbridge are the greatest of friends."

"As a matter of fact, such an idea had not entered my mind," Zena said. "I was wondering why Lord Leconbridge introduced Jacob Hartmann to his wife."

"Hartmann is a very wealthy banker," I answered, "who has been extremely useful to the Conservative Party. He is the first of his family, so to speak, and is engaged in winning a big social position.

Since Lord Leconbridge is a very important member of the Conservative Party, it is quite natural that such an introduction should take place."

"Very interesting," said Quarles; "but are we really required to clear Lady Leconbridge's character? Let us get back to the diamonds. They were kept in the house, I presume?"

"In a safe in the wall in Lady Leconbridge's bedroom."

"The maid knew they were there?"

"Yes."

"It is a point to remember," said Quarles. "We may have to come back to it if we find no other way out of the difficulty. The diamonds were seldom worn, therefore we may a.s.sume that any question of suiting the particular dress Lady Leconbridge had on that night is beside the question. For some reason her husband wished her to wear the diamonds on this occasion. Now, if he had reason to suppose that the jewels were not in the safe, his determination is explained, also his annoyance that his son should attempt to thwart him by agreeing with Lady Leconbridge. However, the diamonds were forthcoming, and at a certain moment the d.u.c.h.ess of Exmoor is able to say that Lady Leconbridge was wearing them. Five minutes later they had disappeared.

You make a point of the fact that expert thieves were not at work that night, Wigan. Do you imagine that an amateur could take the jewels from the lady's neck without her knowing it?"

"You must not lay too much stress upon my point about the expert thieves," I said. "Some gang we know nothing about may have been at work. It certainly is possible to remove a necklace without the wearer being aware of the fact, especially if her mind is fully occupied at the time. In a few moments, no doubt, some movement of her body would have caused Lady Leconbridge to discover the loss, but before this happened her husband was beside her."

"With the banker," said Quarles. "It was at the moment that he brought up Hartmann to present him to his wife that he noticed the diamonds were missing. Is it not possible that Hartmann and the diamonds were in some way connected in his mind?"

"Possible, of course, but----"

"Remember, Wigan, Lord Leconbridge did not mention the subst.i.tution of the diamonds for the pearls to you--a curious omission. I have a theory that the stones were to be a demonstration, a proof of something, and that Lord Leconbridge's irritation arises from the fact that he has not been able to give this proof."

"Proof of what?"

"Ah! that's the question, Wigan; and we have nothing at present to help us to an answer."

"You don't suppose Hartmann was responsible for the jewels not being there?"

"I have no fact to support such a theory."

"Do you suggest that Lady Leconbridge was as anxious that Hartmann should not see the jewels as her husband was that he should?"

"I have not made such a suggestion. Since Leconbridge did not tell his wife why he wanted her to wear the diamonds, he probably did not prepare her for Hartmann's introduction. It is difficult to see what time she would have to rob herself and conceal the spoil."

"Is Lord Leconbridge a poor man?" Zena asked.

"No," I answered; "although I dare say he has plenty of use for his money."

"Perhaps he wanted to sell the diamonds."

"It is possible," said Quarles. "The stones were a means to some end.

Just hand me paper and a pencil, Wigan. My theory grows. Is Lady Leconbridge still in town?"

"I believe she has gone to Gra.s.slands, their seat in Worcestershire."

"Poor lady! The middle of the season, too. Read that, Wigan," and he pa.s.sed me the paper on which he had been scribbling. I read it aloud:

"If the person who took, or found, the diamond necklace lost on the evening of Monday, the 14th inst., at the d.u.c.h.ess of Exmoor's house, in Park Lane, will return the same to Lord Leconbridge, at 190 Hill Street, the said person will save himself or herself all further trouble."

"Get Lord Leconbridge's consent to insert that in the papers," said Quarles. "If he presses you for a reason, you can say that an entirely innocent person is likely to be saved from grave suspicion."

"If you think that Lady Leconbridge is----"

"I do not fancy I mention her name there," said Quarles sharply. "We are after the truth; and, Wigan, when the diamonds are returned, tell Lord Leconbridge not to mention the fact to anyone--anyone, mind, until you have seen them. When you go to see them I want to go with you. You must arrange that as best you can."

I had considerable difficulty in getting Lord Leconbridge to agree to the insertion of this notice, and his reluctance certainly gave support to part of the professor's theory. It looked as if he were bent on concealing some point of importance.

However, he gave his consent, and the day following the appearance of the advertis.e.m.e.nt I heard from him that the necklace had been returned.

I had told him that when I came to see the stones it would be necessary to bring a fellow officer with me, so there was no need to explain Quarles's presence when we went to Hill Street.

The necklace had been packed in wadding in a small, flat, wooden box, had come through the post, unregistered, and had been posted in London. The writing on the brown paper covering was evidently disguised, and might be either a man's or a woman's.

Quarles examined it with a lens, but made no comment.

"You did not expect to regain possession of the necklace so easily, Lord Leconbridge," he said, looking at the stones.

"No."

"A curious robbery, and, since the jewels have been returned, a curious reason for it exists, no doubt. I suppose you cannot give us any helpful suggestion in that direction?"

"No."

"Of course, we have promised not to worry the person responsible any further, but for our own satisfaction----" And then, after a pause, he added: "I suppose it would be a satisfaction to you to get at the exact truth?"

"I don't quite follow the drift of your question," said Leconbridge.

"You have the diamonds; the matter might be allowed to drop if you have any reason to think that, by taking further steps, family affairs might be disclosed which would cause scandal."

For a moment Leconbridge remained silent, his jaw very firmly set.

"I wish to know the exact truth," he said slowly, "but under no circ.u.mstances must the person who has returned the diamonds suffer.

Our word is pledged."

"That is understood," Quarles said. "Let me ask one or two questions, then--rather impertinent ones, but necessary. These stones have been in your family a long while?"