Gio. Giacomo Zamboni, merchant, diplomat and amateur harpsichordist, was born in Florence on 26 July 1683, arrived in London late in 1711 and lived there until his death on 8 April 1753. His career closely parallels that of George Frideric Handel, composer, manager and harpsichordist, who was born in Hanover in 1685, arrived in London late in 1710 and lived there from late 1712 until his death in 1759. When these two men arrived in London, opera in Italian was a novelty at the Queen's Theatre in the Haymarket, which had just begun to employ Italian singers, instrumentalists, composers, librettists and stage designers. During the ensuing decades, there was an unprecedented influx of Italian performers and creators who, like Handel and other ‘outlandish’ personnel at this theatre, found that salaries were higher, working conditions were better and freedom was greater in England than in their own lands. Many therefore stayed as long as possible, and their artistic accomplishments as well as their intricate interactions with British and foreign patrons, diplomats, merchants and musicians are fascinating endeavours that deserve detailed study. At present, the best survey is that in George Dorris, Paolo Rolli and the Italian Circle in London, 1715–44 (The Hague and Paris, 1967), which focuses upon literary accomplishments. The essential base for any such study must, of course, be primary source materials, which include letters and other documents as well as librettos and scores. My hope is that the passages cited below from 458 items, most of which have never before been printed, will significantly broaden our base for study of ‘the Italian circle’ in London between 1716 and 1750.