The Avengers began with the episode “Hot Snow”, in which medical doctor David H Keel (Hendry) investigates the murder of his fiancée, office receptionist Peggy, by a drug ring. A stranger named John Steed, who was also investigating the ring, appears, and together Keel and Steed set out to avenge Peggy’s death in the first two episodes. Steed asks Keel to partner with him, as needed, to solve crimes. Hendry was considered the star of the new series, receiving top billing over Macnee, and Steed did not appear in two of the series’ episodes.
Steed’s importance increased as the first series of The Avengers progressed, and he carried the final episode solo. While Steed and Keel used wit while discussing crimes and dangers, the series also depicted the interplay—and often tension—between Keel’s idealism and Steed’s professionalism. As seen in one of the three surviving episodes from the first series, “The Frighteners”, Steed also had informants among the general population to aid his investigations, similar to the “Baker Street Irregulars” of Sherlock Holmes.
The other regular in the first series was Carol Wilson (Ingrid Hafner), the nurse and receptionist who replaced the slain Peggy. Carol assisted Keel and Steed in cases and in at least one episode (“Girl on the Trapeze”), was very much in the thick of the action but without being part of Steed’s inner circle. Hafner had played opposite Hendry as a nurse in one episode of Police Surgeon. The role of Carol Wilson was initially offered to Jan Watson, who turned it down for another film.
Ingrid Hafner (13 November 1936 – 20 May 1994) was a British actress born in London. Her father was Raoul Hafner, an Austrian helicopter pioneer; her mother, Eileen Myra McAdam, was a descendant of Scottish-born John Loudon McAdam, the road builder.
Career
Film and television
Her first film role was as Ursula in ‘The Quarry’, made for television and directed by John Boorman – his first fiction work as distinct from his documentary films for the BBC in the West of England. She is best remembered for her role as Carol Wilson in the first season of the television series The Avengers. She had previously played Amanda Gibbs opposite Ian Hendry in the series Police Surgeon. She also appeared as Laura Granton in The Main Chance. She appeared as Kay Price in an episode of Public Eye in 1975. On cinema, she played Giselle Dureaux in the 1960 film Bluebeard’s Ten Honeymoons starring George Sanders and later appeared opposite Sanders again in The Amorous Adventures of Moll Flanders (1965). One of her later roles was as Sheila Clare in the HTV series “The Clifton House Mystery” in 1978.
Theatre
Hafner studied at the Bristol Old Vic Theatre School and subsequently joined the Old Vic under Michael Benthall. She played ‘Sylvia’ in The Two Gentlemen of Verona; ‘Lavina’ in Titus Andronicus, ‘Iris’ in Anthony and Cleopatra and ‘Lady Anne’ in Richard III.
Her other theatre work included repertory at Windsor, Colchester, Glasgow Citizens, Richmond Theatre (15 plays), From the French at the Strand Theatre in the West End, Jungle in the Cities at Stratford East and numerous productions at the Bristol Old Vic, including her first appearance there in Cyrano, in which she played Roxanne.
Source: https://en.wikipedia.org/wiki/Ingrid_Hafner