As he was about to pass through, under the curtains, he halted, sniffed the air with much daintiness, then turned to the left and halted again beside a door which flanked the dining room end of the wide hall.
For an instant Simon Cameron stood in front of this.

Then, winding his plumed tail around his hips, he sat down, directly in front of the door, and viewed the portal interestedly, as though he expected a mouse to emerge from it.
It was this seemingly simple action which had so suddenly diverted Gavin from what he had been saying.

He knew the ways of Persian cats, even as he knew the ways of collies.

And both forms of knowledge had more than once been of some slight use to him.
Facing Milo and Claire, he signed to them not to speak.

Then, making sure the house-man had gone upstairs, he walked up to Claire and whispered, pointing over his shoulder at the door which Simon Cameron was guarding: "Where does that door lead to ?" The girl almost laughed at the earnestness of his question, following, as it did, upon his urgent signal for silence.
"Why," she answered, amusedly, "it doesn't lead anywhere.
It's the door of a clothes closet.