The first permanent settlement on Tristan da Cunha was established in 1811 by the American Jonathan Lambert. News of Lambert's claim, which followed ceremonies of possession recognised by both British and American observers, spread throughout the Atlantic. Doubts soon emerged, however, as to Lambert's nationality and as to whether he claimed the island for himself, for the United States or for Britain. This article considers Lambert's settlement, the promulgation of his claim and the re-casting of both Lambert and his claim as British, an act which implicitly recognised the strength of Lambert's claim while appropriating that claim for imperial ends. Because Britons and Americans claimed sovereignty and ownership in the Atlantic in similar ways, the competition between British and American claims to Tristan sheds light on those ways' common British roots.