It's one of the things I love about the books - that there are things which would be a huge deal now, but which DLS is quite unselfconscious about. And some of those moments are merely wonderfully alien (like the casual mention of Mary Thoday's missing front teeth), and others make you go "Oof!" (like the Dowager Duchess's discussion of the Bunter Problem with Harriet, saying "These attached people can be rather difficult", as if he was a particularly possessive dog or something).

Anyway, I bet the soprano saw their relationship in a rather different light, with Peter as her pet English gentleman.