For the scenes set in the '50s, Styles, Corrin, and Dawson play the central roles of Tom, Marion, and Patrick, respectively. Their older counterparts are brought to life by Linus Roache, Gina McKee, and Rupert Everett, respectively. On 2 June, 2021, Deadline reported that "Chewing Gum" star Kadiff Kirwan had joined the cast of "My Policeman."