Lord Van Vernon is part of the aristocracy of the city. He is apparently a very old man. It had been five weeks since he visited The House of Blossoms. The Blossoms and Petals worried that his heart would give out.
Van Vernon had peepholes all over his castle to spy on women in his estate.
The Van Vernons were a family that appears in Thief II. A Lord Van Vernon was with his wife at the Party at Angelwatch. He owned Castle Van Vernon and many factories. He did not know that his wife was unfaithful. Guards had evidence of her affairs, and planned to blackmail her for weapons and armor from her husband.
In this case it seems the roles are switched, and its the current Lord Van Version who is unfaithful. Ironically, the Blossoms sketch their paramours in order to blackmail them later on for more money.