The Moving Toyshop

Blurb

The Moving Toyshop is a comic crime novel by Edmund Crispin, published in 1946. The novel features the detective and Oxford don, Gervase Fen.
It is dedicated to the poet Philip Larkin, Crispin's contemporary at St John's College, Oxford. In chapter 10, reference is made to an undergraduate essay called "The Influence of Sir Gawain on Arnold's Empedocles on Etna", about which Fen comments: "Good heavens, that must be Larkin: the most indefatigable searcher out of pointless correspondences the world has ever known."
The book provided the source for the famous merry-go-round sequence at the climax of Alfred Hitchcock's Strangers on a Train. All the major elements of the scene — the two men struggling, the accidentally shot attendant, the out-of-control merry-go-round, the crawling under the moving merry-go-round to disable it — are present in Crispin's account, though Crispin received no screen credit for it.
The final lines of the book quote Pope's The Rape of the Lock:
With varying vanities, from every part,
They shift the moving toyshop of their heart
In 2006 P.D. James picked it as one of her five most riveting crime novels.