As well as spawning various remakes and sequels, The Quatermass Experiment inspired much of the television science fiction that succeeded it, particularly in the United Kingdom, where it influenced successful series such as Doctor Who and Sapphire and Steel.

The rocket is at first thought to be lost, having dramatically overshot its planned orbit, but eventually it is detected by radar and returns to Earth, crash-landing in Wimbledon, London.

Quatermass and his chief assistant Paterson (Hugh Kelly) investigate the rocket's interior and are baffled by what they find: the space suits of the others are present, and the instruments on board indicate that the door was never opened in flight, but there is no sign of the other two crewmen.

It is not just Quatermass who is interested in what happened to Carroon and his crewmates; journalists such as James Fullalove (Paul Whitsun-Jones) and Scotland Yard's Inspector Lomax (Ian Colin) are also keen to hear his story.

It is clear that there is something critically wrong: Carroon appears to have absorbed the consciousness and physical bodies of the other two crew members and is slowly mutating into a plant-like alien organism.

As the police chase the rapidly transforming Carroon across London, Quatermass analyses samples of the mutated creature in a laboratory and realises that if allowed to spore, the alien will eventually consume all life on Earth.

A television crew working on an architectural programme locates the creature in Westminster Abbey, and Quatermass and British Army troops rush in to destroy it in the hour just before it will bring about doomsday.

[7] Rudolph Cartier had emigrated from Germany in the 1930s to escape its Nazi regime, and joined the staff of the BBC the year before The Quatermass Experiment was made.

[9] He directed important productions such as Kneale's Nineteen Eighty-Four adaptation, the two further BBC Quatermass serials, and one-off plays such as Cross of Iron (1961) and Lee Oswald: Assassin (1966).

[9] The same piece also named The Quatermass Experiment as a high point in his career, calling the serial "a landmark in British television drama as much for its visual imagination as for its ability to shock and disturb".

[citation needed] Brambell, who also appeared in Cartier and Kneale's production of Nineteen Eighty-Four, later became widely known for his roles in the sitcom Steptoe and Son (1962–74) and the film A Hard Day's Night (1964).

The project originated when a gap formed in the BBC's schedules for a six-week serial to run on Saturday nights during the summer of 1953, and Kneale's idea was to fill it with "a mystifying, rather than horrific" storyline.

He and Kneale had collaborated on the play Arrow to the Heart, and worked closely on the initial storyline to make it suit the television production methods of the time.

[14][15] The theme music used was the BBC Symphony Orchestra's 1945 recording of "Mars, Bringer of War" from Gustav Holst's The Planets, conducted by Adrian Boult.

[citation needed] In November 1953, it was suggested that the existing two episodes could be combined and followed with a condensed live production of the latter part of the story for a special Christmas omnibus repeat of the serial.

[citation needed] In 1963, one of the existing episodes was selected as a representative of early British programming for the Festival of World Television at the National Film Theatre in London.

[citation needed] The Times estimated that one year before The Quatermass Experiment was broadcast, in August 1952, the total television audience consisted of about 4 million people.

[21] Following Kneale's death in 2006, film historian Robert Simpson said that the serial had been "event television, emptying the streets and pubs for the six weeks of its duration".

[citation needed] Looking back at The Quatermass Experiment in a 1981 article for The Times, journalist Geoffrey Wansell highlighted the finale:"Westminster Abbey undoubtedly dominated television during the summer of 1953 but it was not just the Coronation of the Queen that sticks in my mind now.

[14] The website of the Museum of Broadcast Communications praises the serial's underlying themes as its most effective feature: "The Quatermass Experiment's depiction of an Englishman's transformation into an alienated monster dramatized a new range of gendered fears about Britain's postwar and post-colonial security.

The Radio Times noted in its preview of the episode that "tonight's story is an enjoyable synthesis of She, The Fly and The Quatermass Experiment—even down to the final battle in a London cathedral".

[citation needed] In April 2005, BBC Worldwide released a boxed set of all their Quatermass material on DVD, containing digitally restored versions of the two existing episodes of The Quatermass Experiment, the two subsequent BBC serials, and various extra material,[32] including PDF files of photocopies of the original scripts for episodes three to six, but the quality of these photocopies is in some cases quite poor.

On 2 April 2005, the digital television channel BBC Four broadcast a live remake of the serial, abridged to a single special, also entitled The Quatermass Experiment.