Edmund Crispin’s Gervase Fen mysteries.
They are extraordinarily fanciful and so extraordinarily well-written that suspension of disbelief comes easily.
In an interesting contrast, the novels are long and rambling and full of side trips and digressions and peopled with quirky characters, whereas the short stories, with a few exceptions, are short and quite bare-boned.
A warning, though: The author takes no prisoners. The stories are replete with classical and literary allusions, so have a dictionary and encyclopedia, real or electronic, at hand. Not looking them up does not interfere with the story itself, but looking them makes it richer.