Ahead of the UK broadcast of the series 1 finale on 1st November 2019, Sky One announced that it has commissioned Hera Pictures to produce an 8-episode second series of the drama. Filming on series two starts in early 2020 for broadcast later that year. Series two picks up the storyline one month on from the events of the series 1 climax.
Four of the actors in the series also have roles on Game of Thrones (2011). These are: "Eleanor", played by Kate Dickie ("Lysa Arryn" on Game of Thrones), "Anna", played by Carice van Houten ("Melisandre/The Red Woman" on Game of Thrones), "George", played by Donald Sumpter ("Maester Luwin" on Game of Thrones), and D.I. Rob Moloney, played by Ryan McKen (a Lannister soldier on Game of Thrones).
In series 2 episode 7 Daniel at the start goes to a shop called the huntsman which is a nod to mark strong in kingsman as it's the same shop used in the kingsman films
"Temple" is based on the Norwegian drama "Valkyrien" (2017), created by Erik Richter Strand.
Beth Milton (Catherine McCormack) is diagnosed with Lancaster's Disease. Lancaster's is characterised by serious facial deformities of which Beth clearly has none.