This remote outpost and part of a British Overseas Territory has an QI past. Once controlled by the East India Company, it became famous as the island prison of Napoleon Bonapart. The recent proposal to build an airport on the Island has highlighted its isolation.
Ascension Island which was a dependency of St Helena until 2009 has an airport used by RAF and US forces. Now all three main islands in the territory have equal status.
Tristan da Cunha is 1180 miles to the south and too isolated to be linked by air to St Helena or apparently anywhere else. To quote a Tristan site:
"No aircraft in use in passenger service today can fly all the way from Cape Town and land in the runway length reasonably available on Tristan."
Since 2009 the territory has been known officially as: Saint Helena, Ascension and Tristan da Cunha.