The Secret Service is a British children's espionage television series, made by Century 21 for ITC Entertainment and broadcast on Associated Television, Granada Television & Southern Television in 1969. Created by Gerry and Sylvia Anderson, and produced by David Lane and Reg Hill, it was the eighth and last Century 21 production to feature – in a manner similar to Thunderbirds and other earlier series – marionette puppet characters as part of a filming technique known as "Supermarionation". Under the direction of Gerry Anderson, who wanted to compensate for the inadequacies of Supermarionation and increase the realism of the format, The Secret Service incorporates footage of live actors for long-distance shots. After The Secret Service, Anderson would not work with puppets again until the 1980s, when he produced Terrahawks in "Supermacromation".

Episodes of The Secret Service follow the adventures of Father Stanley Unwin, a character voiced by and resembling the real-life comedian of the same name. Outwardly the parish priest of a rural English village, Unwin is in fact a secret agent for BISHOP, a covert branch of British Intelligence that combats criminal and terrorist threats from overseas. Aided by junior operative Matthew Harding, the Father answers to his London-based superior – codenamed "The Bishop" – as he would in his public profession. When faced with the challenge of collecting intelligence in a hostile situation, Unwin and Matthew deploy the "Minimiser", a gadget capable of shrinking Matthew to a fraction of his normal size for the purposes of carrying out secret reconnaissance. A nonsensical gobbledegook of Unwin's formulation is used to confuse and distract enemies when required.