I realised my problem is I keep comparing it with One Pair of Hands, the Monica Dickens memoir about being a cook at exactly that time.
This just doesn't feel modern enough to be the late 30s, in either behaviour or technology.
The storyline was very clever but it didn't ring true.
I am also confused by the butler being brought up a Quaker, it seems such an unQuakery job to do when Quakers are so political and obsessed by equality, but perhaps that was/will be explained further.