Damerel is swoonage. And his relationship with Venetia is much more adult and well-matched than Mary and Vidal's. (Vidal get's a mother and, I guess, Mary gets turmoil and adventure?) Still, she knew how to write characters that were alive and place in in well-described-without-being-boring settings.

Earlier you mentioned one of Dorothy L. Sayers books. If Lord Wimsey was one of your influences I can see where Felix gets his somewhat snotty intellectualism. Lord Wimsey maybe didn't mean to be 'noble upperclassman' but he was a product of his upbringing and the attitude slipped in occasionally.