A Son of Perdition by Fergus Hume

Mindful that a premature engagement might lead to gossip, Montrose and his beloved acted with great discretion. They gave vent to their ardent feelings in private, and behaved prudently in public. Certainly the young man paid many visits to Mrs. Barrast's house, and was markedly attentive to her visitor. But it was natural that a bachelor should admire a pretty maid, so people merely remarked indulgently that evidently Montrose was falling in love with Miss Enistor. They little knew that the inevitable had already happened, and in a scandalously short space of time. Mrs. Barrast, with a shrewdness which did her credit, guessed that the couple understood one another better than they would admit; but even she did not guess how far matters had gone. She would have been annoyed had she really known the truth, not because of the private engagement, but for the simple reason that she had not been admitted into the confidence of the lovers.

As it was, all she saw led her to believe that Montrose was conventionally approaching her guest with a view to marriage, and quite approved of his intentions. Therefore she welcomed him to the house, and made use of him and his money. It was only right, she thought, that he should pay for her kindness in forwarding his aims.