Kiran Sonia Sawar (Farah) & Anthony Welsh (Joe) also worked together on episode 4.3, Crocodile (2017) of Black Mirror (2011) as Shazia Akhand & Anan Akhand respectively.
The Central Medical Library that Marnie and Charlie visit is actually the law library at the Law Society of England and Wales, located in Chancery Lane, London.
Anthony Welsh and Niamh Algar both appeared in the film Calm With Horses (also 2019).