Purdey (no other name was ever given, and no indication was made as to whether it was her first or last name) was a former ballet dancer who left the Royal Ballet when she became too tall, and became a secret agent, the natural agility and reflexes from her dancing career readily adapting to martial arts. An exceptional unarmed combatant and markswoman, she was partnered with John Steed and Mike Gambit as the Avengers.
Created by Brian Clemens for the TV series The New Avengers, Purdey debuted in the episode The Eagle's Nest which first aired on 22nd October 1976. The character was played by Joanna Lumley, who would later play Sapphire in Sapphire and Steel.
Purdey appeared in comics for the first time in The New Avengers Annuals, but has since reappeared, unnamed for copyright reasons, in The League of Extraordinary Gentlemen: Century 2009, as one of M's (Emma Peel) MI6 agents, alongside other former female partners of John Steed.