Lisa's Date with Density a child from Josh Weinstein's school days who everyday would get onto the bus with a piece of toast, which had Vaseline on it. A majority of the story is a reference to the film "Rebel Without a Cause". Lisa remarks that Nelson is "like a riddle wrapped in an enigma wrapped in a vest", a reference to "a riddle wrapped in a mystery inside an enigma"; this was Winston Churchill's opinion of Russia at the outbreak of the World War II. In its original broadcast, "Lisa's Date with Density" finished 63rd in ratings for the week of December 9–15,
The Riddle of the Sphinx (Inside No. 9) thus far of the third series, and even "one of the best" episodes ever. It was praised by Ben Lawrence of Telegraph.co.uk for its "near brilliance", while Dessau characterised it as a "beautiful constructed playlet". At the end of the fourth series, Butler listed "The Riddle of the Sphinx" as the second strongest episode of "Inside No. 9", describing it as "sheer brilliance". He listed "The 12 Days of Christine" as the strongest. The episode was widely noted as both very dark, and very clever. Dessau characterised it as the cleverest episode of "Inside No. 9", and the freelance journalist