This dictionary of etymology says meter maid (with a space) was first used in 1957 for a person who checks parking meters.
The parking meter itself was introduced in 1935.
So how does a reclusive artist-draftsman Achilles Rizzoli, about to self-publish a novel, come up with the pseudonym “Peter Metermaid” - in 1931?
Rizzoli evidently was gifted with spiritual visions. But was he able to predict the future without knowing it?