A Question of Proof

A Question of Proof is a 1935 detective novel by Cecil Day-Lewis, written under the pen name of Nicholas Blake. It is the first in a series of novels featuring the private detective Nigel Strangeways. Day-Lewis chose to write under an assumed name as he feared writing in the popular detective genre would harm his growing reputation as a serious-minded poet. Consequently, the publishers Collins advertised the book as being written by a "well-known writer" using a pen name. It was a commercial success selling around 200,000 copies in Britain and launching Day-Lewis, who quickly did become widely identified as the author, as one of the leading writers of the Golden Age of Detective Fiction.