Dorothy Macmillan (n�e Cavendish), wife of Harold Macmillan (1957-63)
Elizabeth Douglas-Home (n�e Alington), wife of Alec Douglas-Home (1963-64)
Edward Heath (1970-74) was not married
Mary Wilson (n�e Roy), wife of Harold Wilson (1964-70, 1974-76)
Audrey Callaghan (n�e Moulton), wife of James Callaghan (1976-79)
Denis Thatcher, husband of Margaret Thatcher (1979-90)
I guessed it would be Presidents First Wives, or Prime Ministers wives. Went to Wiki - searched both for Audrey - which I thought would be the rarest name, and Voila !
I've seen this before. There is an alternative, equally-valid answer.
Denis fits if they are to be spouses of Prime Ministers.
Norma fits if they are to be wives of Prime Ministers.