This story aired in the following known countries. They are listed in chronological order according to known airdate. If no month is noted, the actual airdate is not confirmed, and is a close approximate. (Refer also to Selling Doctor Who for expanded airdates.)
- The story (in b/w) was assessed and rejected by the censors in Australia in October 1973. This also meant that New Zealand, Hong Kong, Singapore and Gibraltar could not purchase.
- The story was also not offered to Middle Eastern countries, so it didn't air in Saudi Arabia or United Arab Emirates with the rest of the season.
- CONSPIRACY THEORY: Not selling to the Middle East might have been a deliberately tactful move by the BBC, because the serial did not necessarily paint the oil/chemical industry in a very good light...
- The only country to purchase was Canada, and the serial screened in Vancouver and Toronto around the same time.
- The Australian censors were asked by the ABC to reassess the story for a run of repeats in 1978, and this time it was cleared (and in screened in colour (the tapes received in 1973 had been retained in Australia). This also meant that New Zealand could buy the serial; it screened mid-way through a run of Tom Baker stories.
- The serial was also issued to the USA in mid-1983, as part of a package of 14 full colour Jon Pertwee stories:
- Canada was also offered the serial again in the 1990s (?).