The Liver Birds "Man is the dog, and woman is the bone. He eats the best of you, and buries the rest of you, and when his dish is empty—he'll dig you up again." This would be the last series with Beryl; as Polly James explained: "The reason I left the programme in the end was that I felt I was in danger of caricaturing what was already a pretty outrageous character." Producer Sydney Lotterby had to find a new leading actress to keep the series going after Polly James' departure. In 1971 he'd replaced Pauline Collins with Nerys Hughes, and Hughes herself
The Liver Birds Stars", a programme shown annually on Christmas night, when leading BBC performers appeared in short versions of their series, typically 5–10 minutes long. Carla Lane became sole writer for the fourth series. She felt it was now time for the Liver Birds to start thinking about longer-term relationships with men. John Nettles played Paul, Sandra's (frustrated) boyfriend, and Jonathan Lynn played Robert, Beryl's boyfriend. "I always wanted The Liver Birds not to be too keen about marriage—not to down it—but not to be out to get a boyfriend to marry," Lane explained. Beryl's mother (Sheila Fay) voiced the critical view: