Though James Cox was celebrated during his lifetime, the date and place of birth are unknown. According to the Clockmaker's Records, J. Cox was established at the Racquet Court in London in 1749 and a trade-card now in the British Museum, engraved as his address Racquet Court, Fleet Street, at the sign of the Golden Urn. From 1756-1759 he was in partnership with the clockmaker Edward Grace when, according to a later trade-card in the British Museum, Cox was at the Golden Urn, Shoe Lane. Nothing further is known of his activities between 1751-1766. Objects signed by James Cox belong to the British Royal Collection, the British Museum, the Louvre, the Metropolitan Museum, the Walters Art Gallery, and the private collectors.