Uhhhhhmmmm, well, I think this was written in the late 70s, in England, by someone longing for even older times. It's sorta depressing, because it's suburban, and everyone is a bit too polite to ask the suspects direct questions.
As a historical vignette, it's quite amusing, but not a romp of a murder-mystery omnibus.
If you are 6.5 months pregnant and having sleep issues, anything will do.