Lessingham accepted the situation quite coolly, and placed the hat carefully on his head.

“It doesn’t feel particularly comfortable,” he remarked.

“That may be,” Sir Henry suggested, “because you have it on wrong side foremost.  If you’d just turn it round, I believe you would find it a very good fit.”

Lessingham at once obeyed.  Sir Henry regarded him with admiration.

“Excellent!” he exclaimed.  “Look at that, Philippa.  Might have been made for him, eh?”

Lessingham looked at himself in the glass and removed the hat from his head with, some casual observation.  He was entirely at his ease.  His host turned towards the door, which Mills was holding open.

“Captain Griffiths, sir,” the latter announced.

Sir Henry greeted his visitor briefly.

“How are you, Griffiths?” he said.  “Glad to see you.  Excuse my costume, but I am just back from a fishing expedition.  We are all admiring Mr. Lessingham in his magic hat.”

Captain Griffiths shook hands with Philippa, nodded to the others, and turned towards Lessingham.

“Put it on again, there’s a good fellow, Lessingham,” Sir Henry begged.  “You see, we have found a modern version of Cinderella’s slipper.  The hat which fell from the Zeppelin on to Dutchman’s Common fits our friend like a glove.  I never thought the Germans made such good hats, did you, Griffiths?”

“I always thought they imported their felt hats,” Captain Griffiths acknowledged.  “Is that really the one with the German name inside, which Miss Nora brought home?”

“This is the genuine article,” Lessingham assented, taking it from his head and passing it on to the newcomer.  “Notwithstanding the name inside, I should still believe that it was an English hat.  It feels too comfortable for anything else.”

The Commandant took the hat to a lamp and examined it carefully.  He drew out the lining and looked all the way round.  Suddenly he gave vent to a little exclamation.

“Here are the owner’s initials,” he declared, “rather faint but still distinguishable,—­B.  M. Hm!  There’s no doubt about its being a German hat.”

“B.  M.,” Sir Henry muttered, looking over his shoulder.  “How very interesting!  B. M.,” he repeated, turning to Philippa, who had recommenced her knitting.  “Is it my fancy, or is there something a little familiar about that?”

“I am sure that I have no idea,” Philippa replied.  “It conveys nothing to me.”

There was a brief but apparently pointless silence.  Philippa’s needles flashed through her wool with easy regularity.  Lessingham appeared to be sharing the mild curiosity which the others showed concerning the hat.  Sir Henry was standing with knitted brows, in the obvious attitude of a man seeking to remember something.

“B.  M.,” he murmured softly to himself.  “There was some one I’ve known or heard of in England—­What’s that, Mills?”