I was privileged recently to visit the Pepys Library at Magdalene College, Cambridge and to see the 17th century trade cards collected by the great diarist. Samuel Pepys, among his many other attributes, was a pioneer ephemerist. In the Pepys Library are preserved his volumes of approx. 1740 ballads and other 'vulgaria' (chapbooks, etc). In the London and Westminster volumes are some 41 of the earliest trade cards I know, together with many other 17th century ephemera: 'tickets of invitation, (including a ticket for the Society of Gentlemen Lovers of Musick, 1696) and several funeral invitations.
The ephemera are individually catalogued in vol. 3 of the Catalogue of Pepys Library at Magdalene College, Cambridge ed. Robert Latham (1980), pp. 39-43, which references the article in The Connoisseur, XCII (1933): Samuel Pepys. His trade cards by Ambrose Heal (whose collection of, mainly 18th century, trade cards is in the British Museum). A further article by Heal: 17th century booksellers' & stationers' trade cards appeared in Alphabet & Image 8 (Dec 1948).