The opening moment of the prologue of this episode, revealing the Duke of Windsor coughing up blood into a toilet, mirrors the opening moment of the Series 1 premiere, with his brother King George VI seeing blood in his spittle in the toilet.
Olivia Colman (Queen Elizabeth II) and Andrew Buchan (Andrew Parker-Bowles) previously worked together on the ITV drama Broadchurch (2013) playing Ellie Miller and Mark Latimer, respectively.