Of a sudden he remembered that he had been a trifle surprised to perceive that Colonel Grey had been carrying gloves when he had found him in the rose-garden with Lady Loudwater.
His surprise had passed quickly enough.

He had decided that the life in the trenches had not weakened Colonel Grey's habit, as a fastidious man about town, of taking care of his hands.

He remembered, too, that at his first interview with him he had observed that his hands were uncommonly well shaped and well kept.
He did not suppose that Colonel Grey had come to the Castle on the night of the murder wearing gloves with the deliberate intention of killing Lord Loudwater without leaving finger-prints.

But suppose that, as he came away from a distressing interview with Lady Loudwater, the knife on the library table had caught his eye and his gloves had been in his pocket?
Mr.Flexen took out his pipe, lit it, and moved to an easy-chair to let his brain work more easily.

He tabulated his facts.
Colonel Grey had gone through the library window at about twenty minutes past ten.
Hutchings had gone through the library window at half-past ten.
The mysterious woman had gone through the library window at about ten minutes to eleven.
She came out of the library window at about a quarter-past eleven after a violent quarrel with Lord Loudwater.
Colonel Grey came out of the library window at about twenty-five minutes past eleven, after a distressing interview with Lady Loudwater, apparently in a very bad temper.
James Hutchings had come out of the library window at about half-past eleven, also, if William Roper might be believed, furious.
Lady Loudwater had come through the library window at a quarter to twelve, and gone back through it at five minutes to twelve.
Each of the last three had passed within fifteen feet of Lord Loudwater, dead or alive, both on entering and on coming out of the Castle.