Which Scottish island was used to shoot the 1937 film "The Edge of the World"?

“The Edge of the World” is a 1937 British film directed by Michael Powell, loosely based on the evacuation of the Scottish archipelago of St Kilda. The title is a reference to the expression "ultima Thule," coined by Virgil. The film stars Niall MacGinnis, Belle Chrystall and John Laurie.

The film is the story of the depopulation of an isolated outer island of Scotland as, one by one, the younger generation leaves for the greater opportunities offered by the mainland, making it harder to follow the old ways of life there. Steam trawlers from the mainland threaten its survival as a fishing port. Peter Manson, one of the community's leaders, resists evacuating to the mainland, though his son Robbie is about to leave the island himself. Meanwhile, Robbie's twin sister plans to marry his best friend, Andrew Gray. Andrew and Robbie argue over evacuation and decide to settle the matter by racing to the top of a cliff. The race ends in tragedy, which tears apart the families of Manson and Gray. The island is completely abandoned.

Powell was not allowed to film on St Kilda, but found another suitable island, Foula in the Shetland Islands to the north of Scotland; Foula is one of the United Kingdom's most remote permanently inhabited islands. As depicted in the film the island is referred to as "Hirta", which is the actual name of the formerly inhabited main island of the St Kilda archipelago, but a map that appears two minutes into the film actually shows Foula.