The Second Marquis of Rockingham (1730–1782) was a devoted collector of Roman Imperial coins. The letters here published cover only a limited period of his collecting activity, but they are significant for his association with Mr. James Byres, his agent in Rome. They make clear the enthusiasm of Lord Rockingham, and the involvement of Mr. Byres in the sometimes murky conditions of the Italian market. The letters include details on a number of historic personalities as well as minor figures in the world of dealers. Finally, an effort is made to examine the attitudes of noble collectors in the eighteenth century and before to the coins they acquired, and the important sequel at the end of the century.