The Riddle of the Sphinx (Inside No. 9) was characterised by Pemberton as a thriller in the style of Anthony Shaffer's 1970 play "Sleuth", while Shearsmith identified the episode as particularly theatrical, in the style of "Sleuth" and Ira Levin's 1978 play "Deathtrap". BBC executives, according to Shearsmith, saw the episode as a cross between "Sleuth" and Willy Russell's 1980 play "Educating Rita" that read as if it had been authored by psychopaths. The executive producer Jon Plowman suggested that the first half of the episode plays out like a radio play. The word-play and tea-drinking in this part of the episode are, in the writers' opinion, very
George Valentine (poet) George Valentine (poet) George Donald Valentine (1877-1946) was a Scottish sheriff, and writer of romantic-style short stories, plays and verse. He graduated from the University of Glasgow and was considered for Examinerships in Mathematics and Natural Philosophy at both Glasgow and St Andrews Universities. G. D. Valentine wrote both under his own name and the pseudonym, George Henderland. Valentine's first published work was "The Heart of Bruce", a long poem, taken up by Alexander Gardner of Paisley in 1912. In the 1920s, two further original works, "Reasons of State" and "Saul: A Dramatic Poem" appearsed under the same imprint. It