If his appearance was superficially against him, it had the advantage of making his solid merits something of a surprise.

He had kept notebooks; he knew a great deal about pictures.
He could compare different examples in different galleries, and his authoritative answers to intelligent questions gained not a little, Mary felt, from the smart taps which he dealt, as he delivered them, upon the lumps of coal.

She was impressed.
"Your tea, William," said Katharine gently.
He paused, gulped it down, obediently, and continued.
And then it struck Mary that Katharine, in the shade of her broad-brimmed hat, and in the midst of the smoke, and in the obscurity of her character, was, perhaps, smiling to herself, not altogether in the maternal spirit.

What she said was very simple, but her words, even "Your tea, William," were set down as gently and cautiously and exactly as the feet of a Persian cat stepping among China ornaments.

For the second time that day Mary felt herself baffled by something inscrutable in the character of a person to whom she felt herself much attracted.
She thought that if she were engaged to Katharine, she, too, would find herself very soon using those fretful questions with which William evidently teased his bride.