The location used for Doyle's flat was also used as Shirley Glass's flat in The Sweeney Series 3 Pay Off (1976): the stained glass in the front door and the green spiral staircase from the living room to the bedroom are recognisable in both episodes.
Ann's photograph of her father and his RAF colleagues has the names of the men written on the back. One of the names given is Dusty Miller - the name of the lighting cameraman for this episode and several others.
Guest star Patricia Hodge and Lewis Collins studied at the London Academy of Music and Dramatic Art together.