English gunsmith, tool-cutter and type-founder William Caslon published A Specimen of Printing Types, by W. Caslon and Son, Letter Founders, London in 1764. Bliss identified a unique copy of this work, probably a proof copy, dated 1763, in the American Antiquarian Society. He also identified two variant imprints, the first "Printed by Dryden Leach," and another "Printed by John Towers." I have linked to the copy in the Cary Graphics Collection at the Rochester Institute of Technology.
Caslon, known for the Caslon typeface, became a type-founder in 1720. He was was the first really competent cutter of punches and caster of types in England, and the first typefounder to develop a large-scale business. Caslon's success virtually stopped the importation of Dutch types, upon which English printers had relied for so long. Prior to his first specimen book Caslon published a broadside specimen sheet in 1734.
Carey S. Bliss reproduced the Dryden Leach issue of Caslon's specimen book in A Pair on Printing (1982).