What if the writer were indeed Iris Woolstan, and her motive quite disinterested?
What if she did not allude to herself at all, but was really pained at the thought of his making an insignificant marriage, when, by waiting a little, he was sure to win a wife suitable to his ambition?
Of this, too, Iris might well be capable.

Her last letter to him had had some dignity, and, all things considered, she had always shown herself a devoted, unexacting friend.

It seemed more likely, it seemed much more likely, than the other conjecture.
Nevertheless, suppose Miss Tomalin _had_ taken this romantic step?
The supposition involved such weighty issues that he liked to harbour it, to play with it.

He pictured himself calling in Pont Street; he entered the drawing-room, and his eyes fell at once upon Miss Tomalin, in whose manner he remarked something unusual a constraint, a nervousness.
Saluting, he looked her fixedly in the face; she could not meet his regard; she blushed a little-- Why, it was very easy to determine whether or not she had sent that letter.

In the case of Iris Woolstan, observation would have no certain results, for she must needs meet him with embarrassment.