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
Shirley Valentine (film) the seashore in the country where the grapes were grown, and later invites her to travel around the nearby islands for a day on his brother's boat. Costas promises not to try to seduce her, while nonetheless bolstering her self-confidence in her own attractiveness. As Shirley prepares for the trip, Jane returns and begs for forgiveness for abandoning her; Jane is then stunned to find that Shirley has made plans on her own and will be going out with Costas imminently. Enjoying the day out, Shirley decides to swim in the sea; lacking a swimsuit she swims naked instead with