One of the most celebrated passages in Edward Gibbon’s autobiography identifies the moment when the idea for what would become his magnum opus, The History of the Decline and Fall of the Roman Empire, first came to him:

It was at Rome, on the 15th of October 1764, as I sat musing amidst the ruins of the Capitol, while the barefoot friars were singing vespers in the Temple of Jupiter, that the idea of writing the decline and fall of the city first started to my mind.

It is a carefully staged scene: a citizen of the new world empire musing alone at the ruined heart of the world empire of antiquity. But was Gibbon alone? Almost the first thing that he did on arrival in Rome in the autumn of 1764 was to engage the services of an antiquary, an expert guide to the history and artistic treasures of the city. This guide, James Byres of Tonley in Aberdeenshire (1733–1817), was an architect, archaeologist, historian and man of taste, and one of the shadowy community of British exiles in Rome. In fact, Byres was a citizen of a rich cluster of shadow communities: