Suppose he said, "She is _not_ my friend's wife ?" Female curiosity would inevitably put the next question, "Who is she ?" Suppose he invented an explanation?
The explanation would take time, and time would give his wife an opportunity of discovering Lady Jane.

Seeing all these considerations in one breathless moment, Mr.Vanborough took the shortest and the boldest way out of the difficulty.

He answered silently by an affirmative inclination of the head, which dextrously turned Mrs.Vanborough into to Mrs.Delamayn without allowing Mr.Delamayn the opportunity of hearing it.
But the lawyer's eye was habitually watchful, and the lawyer saw him.
Mastering in a moment his first natural astonishment at the liberty taken with him, Mr.Delamayn drew the inevitable conclusion that there was something wrong, and that there was an attempt (not to be permitted for a moment) to mix him up in it.

He advanced, resolute to contradict his client, to his client's own face.
The voluble Lady Jane interrupted him before he could open his lips.
"Might I ask one question?
Is the aspect south?
Of course it is! I ought to see by the sun that the aspect is south.

These and the other two are, I suppose, the only rooms on the ground-floor?
And is it quiet?
Of course it's quiet! A charming house.