The first episode was broadcast by the BBC on November 16, 1969 and a further twenty-five episodes were made. The twenty sixth episode was broadcast on November 10, 1972 and the final Clangers programme was an election special on October 10, 1974. (This last episode has not been seen since its original broadcast, although it reportedly still exists.)
The program featured a number of small creatures living in peace and harmony on - and in - a small, hollow blue planet far away, nourished by Blue String Pudding, and Green Soup harvested from the planet's volcanic soup wells by the Soup Dragon. The Clangers looked similar to mice, though they were pink, wore clothes, and spoke in whistles (of a modulating type: the Clangers' sounds were produced on swanee whistles).
The series creators have said that the Clangers, living in vacuum, did not actually communicate by sound, but rather by a type of nuclear magnetic resonance, which was translated to audible whistles for the human audience. These whistles followed the rhythm and intonation of a script in the English language, including swear-words! The action was also narrated by a separate voice-over from Postgate, however the series was shown without narration to a group of overseas students, who felt that the Clangers were speaking their language.
The word "Clanger" is said to derive from the sound made by opening the metal cover of one of the creatures' crater-like burrows (the silence of the vacuum notwithstanding). The covers bear a suspicious resemblance to dustbin lids, and are there to protect the burrows against meteorite impacts.
The principal characters are:
Mid-80's indy-rock band The Soup Dragons were named in honour of the show.
The characters are still very popular. For instance they make guest appearances on the radio programme I'm Sorry I Haven't A Clue, playing parts in plays not conventionally known to feature Clangers. Whistling soft toys of Major, Mother, Small and Tiny Clanger are currently available.
 It is interesting to note that the Clanger toys' voice-boxes actually play a line "spoken" by Major Clanger on the occasion when the large doors of the main cave jam as they are opening: "Oh sod it! The bloody thing's stuck again!"