SOLVED. British Crime Comedy. School librarian investigating murder with possibly autistic teenage boy, Christie obsessed side kick. [s]

[Tanya]

Trying to find this mystery book. I can remember:

It is set in a British town with 2 schools and contains a map of the location.
There is a murder in a school and the librarian and a teenage boy, one of the students investigate.
It is quite funny, doesnt take itself too seriously.
The librarian has a bit of a relationship with the boy's mum. I read it recently but my kindle has deleted all knowledge of it when I must have read it on the device.

[Mai]

Maybe Who Killed Miss Finch?: A quirky whodunnit with a heart by Peter Boon? It came up in a search and, from the summary and reviews, it sounds close to your description!

[Tanya]

Phew! Thanks so much. I was trawling the internet half of last night to no avail. That's it!