Beatrice Protheroe is a minor character in The New Statesman, and is played by actress Vivien Heilbron. She only appeared in the first three episodes of Series One.
Beatrice is first seen briefly in "Happiness Is A Warm Gun" sharing a bed with Sarah B'Stard. Sarah had just gotten off the phone to her husband Alan following his Commons victory on the passing of a bill that would arm the police. As she reclines with Beatrice into her bed, it becomes obvious that Sarah is not only bisexual, she is also committing adultery.
In "Passport To Freedom" she reveals she is Alan's political agent, and is seen dining with Sarah as Sarah celebrates inheriting over £200,000 in shares for the Ocelot Motor Company; bequeathed to her by her dead uncle.
In "Sex Is Wrong" it is implied that Beatrice is also having a relationship with Alan. Alan has his hand up her skirt at the beginning of the episode, and by episode's end he presumes a knock on his hotel room door late at night is Beatrice, when in fact it is a lustful Lady Virginia Imery. In the same episode, Beatrice unwittingly reveals Alan's deception to Lady Virginia by calling him by his real name at the Conservative Party Conference in Blackpool.