The series charted the ups and downs of two 'dolly birds' sharing a flat on Huskisson Street, in Liverpool. The series concentrated on the problems encountered by the two young single women when dealing with boyfriends, work, parents and each other. Dressed in the best 1970s fashions they looked for romance in a loose female equivalent of The Likely Lads.
The pilot and Series 1 starred Pauline Collins as Dawn and Polly James as Beryl Hennessey. In Series 2, Nerys Hughes debuted as Sandra Hutchinson, replacing the Dawn character for the rest of the programme's run. The Beryl and Sandra pairing is generally regarded as the programme's best period. Beryl was the more common one, while Sandra was softly spoken and more refined. This was mainly due to the influence of her snobbish and overbearing mother played by Mollie Sugden. Carla Lane drew on her own mother for the character - "Mrs. Hutchinson, I think she was my mother. I'm sure she was my mother." Beryl's (common) mother, (the Hennesseys live in Bootle, a working class district to the north of the city), was played by Sheila Fay. Elizabeth Estensen as Carol Boswell replaced Beryl from Series 5 onwards.
The title derives from the name given to two sculpted birds perched atop the Royal Liver Building at Pier Head in the city of Liverpool. Michael Mills, (the aforementioned Head of Comedy at the BBC), came up with the title - a title which Carla Lane did not initially like.[2] The title song for the series was sung by The Scaffold. The group included Mike McCartney (brother of former Beatle Paul McCartney) and the poet Roger McGough.