Precisely the point to which the Sergeant’s mind also had turned!  The knowledge which he possessed—­that half of the secret—­and which his companion did not, might be very material to a solution of the problem; the Sergeant did not mean to share it prematurely, without necessity, or for nothing.  But surely it had a bearing on the case?  Dull-witted as he was, the Sergeant seemed to catch a glimmer of light, and mentally groped towards it.

“Well, we can’t sit here all night,” said the stranger in good-humored impatience.  “I’ve a train to catch.”

“There’s no train up from here to-night.”

“There is from Sprotsfield.  I shall walk over.”

The Sergeant smiled.  “Oh, if you’re walking to Sprotsfield, I’ll put you on your way.  If anybody was to see us, Boomery, for instance, he couldn’t complain of my seeing an old pal on his way on Christmas night.  No ’arm in that; no look of prowling, or spying, or such like!  And you are an old pal, ain’t you?”

“Certainly; your old pal—­let me see—­your old pal Percy Bennett.”

“As it might he, or as it might not.  What about the—­” He pointed to Percy Bennett’s breast-pocket.

“I’ll give it you outside.  You don’t want me to be seen handing it over in here, do you?”

The Sergeant had one more question to ask.  “About ’ow much d’ye reckon there might be by now?”

“How often have they been to London?  Because they don’t come to see my friends every time, I fancy.”

“Must ’ave been six or seven times by now.  The game began soon after Boomery and I came ’ere.”

“Then, quite roughly, quite a shot, from what I know of the deals we—­my friends, I mean—­did with them, and reasoning from that, there might be a matter of seven or eight thousand pounds.”

The Sergeant whistled softly, rose, and led the way to the door.  The gentlemanly stranger paused at the bar to pay for the brandy, and after bidding the landlord a civil good-evening, with the compliments of the season, followed the Sergeant into the village street.

Fifteen minutes’ brisk walk brought them to Hinton Avenue.  At the end of it they passed Doctor Mary’s house; the drawing-room curtains were not drawn; on the blind they saw reflected the shadows of a man and a girl, standing side by side.  “Mistletoe, eh?” remarked the stranger.  The Sergeant spat on the road; they resumed their way, pursuing the road across the heath.

It was fine, but overclouded and decidedly dark.  Every now and then Bennett, to call the stranger by what was almost confessedly a nom-de-guerre, flashed a powerful electric torch on the roadway.  “Don’t want to walk into a gorse-bush,” he explained with a laugh.

“Put it away, you darned fool!  We’re nearly there.”

The stranger obeyed.  In another seven or eight minutes there loomed up, on the left hand, the dim outline of Mr. Saffron’s abode—­the square cottage with the odd round tower annexed.