Between 1899 and 1902, Anglo-French archaeologist George Bonsor carried out an exploration of the Scilly Isles (United Kingdom). At that time the archipelago was believed to be the Cassiterides or Tin Islands mentioned by authors such as Strabo, Pliny the Elder and Ptolemy – an idea first posited by William Camden in his Britannia (1586). Adopting Camden’s theory and guided by ancient literature on the Cassiterides – which refers to the Phoenicians as the first controllers of this trade route – Bonsor sought traces of the Phoenicians and their tin trade in the Scilly Isles, becoming the first person to conduct such research from an archaeological perspective. Not having found any evidence, his exploration remained unpublished and went mostly unnoticed in debates about the Tin Islands over following decades. This paper presents a brief historiographical account on the Cassiterides before and after the explorations, as well as a critical analysis of Bonsor’s field notes regarding his use of ancient sources and his archaeological method. The analysis carried out suggests that Bonsor’s archaeological exploration has been overlooked thus far and that a new assessment of his work is required.