It had deceived no one, least of all S.K.R.

"The man himself" stood on the very hearth of the club, with his back to the fireplace.

It was the attitude of mastery, a mastery the more superb because unconscious.
His eyes too, were the eyes of a master, twinkling a little as to their light, but steady as to their direction, being fixed on Maddox.
He was smiling.
There was nothing malignant, or bitter, or sardonic about that smile.
No devilry of delight at their confusion.

No base abandonment of the whole countenance to mirth, but a curious one-sided smile, implying delicacies, reservations.

A slow smile, reminiscent, ruminant, appreciative; it expressed (if so subtle and refined a thing could be said to express anything) a certain exquisite enjoyment of the phrases in which they had defined him.
And seeing it, Maddox said to himself, "He isn't a gentleman.