Established in 1957 by editor-director Gerry Anderson and cinematographer Arthur Provis, following the liquidation of their employer Polytechnic Films, AP Films ("Anderson Provis") was set up. They took with them producer Reg Hill, cinematographer John Read and secretary Sylvia Thamm (who would later become Anderson's second wife). The company was created with the intention of it becoming a conventional film production house.
With no commissions and funds running low, APF were approached with an offer of collaboration with children's author Roberta Leigh and her colleague Suzanne Warner to produce the puppet TV series The Adventures of Twizzle for Associated-Rediffusion. With some reluctance, the company took on the commission and the programme was such a success that it immediately led to a further collaboration with Leigh for the first series of Torchy the Battery Boy (also for Associated-Rediffusion).
In 1959, Authur Provis left the company amicably following disagreements with Anderson over future strategy. APF then went on to make its first wholly independent production of Four Feather Falls, a puppet Western created by Barry Gray (better known for his musical contributions to the company's productions), for Granada Television. In 1960, APF made a live-action thriller feature film, Crossroads to Crime, for Anglo-Amalgamated, and a series of TV advertisements for a London travel company.
Returning to filming with puppets, but with a change in direction and the adoption of a technique by which mouth movements were synchronised with recorded dialogue (a process that Anderson dubbed "Supermarionation"), the company then filmed its best-known productions – a succession of futuristic science-fiction action-adventure series, all made for Associated Television. Supercar was made between 1960 and 1961, Fireball XL5 in 1962, Stingray in 1964 – the first British children's TV series to be filmed exclusively in colour – and Thunderbirds between 1964 and 1966. Following the completion of Fireball XL5, ATV owner Lew Grade had purchased the company, becoming managing director, with the Andersons, Reg Hill and John Read remaining as directors.
Immediately following completion and the first TV screening of Thunderbirds in 1965, AP Films was renamed Century 21 Productions to align it with its growing merchandising sister companies Century 21 Merchandising, Century 21 Toys and Century 21 Music.
All Century 21's productions featured an opening ident(ification) of a field of pale concentric circles, which form a moving, off-centre tunnel against a blue background, into which flies a yellow dart which penetrates through a gap in the Century 21 logo already situated in front, at which point everything stops moving. This was accompanied by a typical Barry Gray string glissando and the caption "A Gerry Anderson Century 21 Television (or Cinema) Production" - the logo being part of that. This sequence was first used for the two Thunderbirds film sequels (Thunderbirds Are Go – premiering 12 December 1966 – and Thunderbird 6 in 1968), and two more Supermarionation series for ATV, Captain Scarlet and the Mysterons (broadcast between 1967 and 1968) and Joe 90 in (1968–69).
A live-action film, Doppelgänger (a.k.a. Journey to the Far Side of the Sun) followed in 1969. That same year, Century 21 made its final puppet TV series, the rarely seen The Secret Service (which combined live action with puppetry), after which its puppet studios closed and its merchandising and publication subsidiaries contracted rapidly. Its first and only all-live action TV series, UFO (1970), proved to be its last production. Although a second series of UFO was planned, the project failed to progress beyond substantial pre-production work.