The opening scene takes place in September 1931 and the closing scene of season one takes place in January 1937. Nancy ages from 26 to 32 years old; Pam was 23-29, Tom was 22-28, Diana was 21-26, Unity was 17-22, Jessica was 14-19, and youngest sister Deborah was 11 to 16 years old during this time period.
Bessie Carter who plays Nancy Mitford said she has "been weirdly connected to Nancy for ages." Carter performed the audio-book narration for Mitford's The Pursuit of Love and researched the author during the process. She learned Mitford worked at St Mary's Hospital during the war, the hospital where Carter herself was born and Mitford's house in Maida Vale was only 10 minutes from her own home. Carter and Mitford are both alumnae of Francis Holland School.
Executive Producer Matthew Mosley is the great-grandson of British Union of Fascists founder Oswald Mosley and his first wife Lady Cynthia Curzon. Sir Oswald Mosley is portrayed by Joshua Sasse in this series.
Bessie Carter Calam Lynch and Jack Michael Stacey were all in Bridgerton or it's spin off Queen Charlotte: A Bridgerton Story. Bessie and Calam were both in Bridgerton Bessie as Prudence Featherington a major character and Calam played Theo Sharpe a potential love interest to one of the Bridgertons. Jack Michael Stacey was in the spin off playing Queen Charlottes son Prince Edward the future father of Queen Victoria.