[iPlayer link, available for a few weeks]
Many of the clues are name-checked or worked through in the TV episode, but in particular…
After a MYSTERY GUEST tries to use PUFFERFISH poison on a KNOW IT ALL in room NEUN/9 to cause ASPHYXIATION, the intended recipient reveals ‘I SWAPPED CUPS’. However, by the end, he [Nigel Hector Squires] also dies, hence RIP NHS.
Guardian article about the puzzle and episode [here], that reveals that the puzzle was set by Steve Pemberton who appears as ‘Sphinx’ in the show. It also mentions that they changed the clue for 3dn from the TV version “A disturbed setter concealed a tiny amount. Why, it’s enough to take your breath away” as it would not have met the crossword editor’s standards[!].
Link back to original [blog]