Layton Williams auditioned six times, originally for the part of Simon. Olivia Colman was the first person to be cast.
The big musical medley street scene took nine hours to film.
Author Simon Doonan wanted the writer Jonathan Harvey to feel free to be liberal and "surprise him" with his scripts; he only requested that the names be changed, as he felt the series should be inspired by his story, not literally his story.
Olivia Colman (Debbie Doonan) & Meera Syal (Aunty Hayley) also worked together on seven episodes of Broadchurch (2013) as Ellie Miller & Judge Sonia Sharma respectively.