The director of the two previous films, Paul King, has decided not to direct this installment. However, he pitched the idea for this third film and is involved with the screenplay.
Announced before the second entry had begun filming or casting.
As of March 2022, it is currently unconfirmed if the original casting of Judy Brown (Madeleine Harris) and Jonathan Brown (Samuel Joslin) will return, as by now, their characters clearly would be a lot older visually, in their mid/late teens, or even early 20s, and couldn't play the characters ages as originally written by (Sir) Michael Bond. Although most of the other core central adult family cast actors have confirmed they will return.
Rachel Zegler was initially supposed to play Gina Cabot, however she was removed from the project due to the SAG-AFTRA strike. She was replaced with newcomer Carla Jones.
Sally Hawkins will not return as Mrs. Brown. She will be replaced by Emily Mortimer.