Born near the Caslon foundry and son of Caslon I’s washerwoman, he was apprenticed to Caslon II in 1748. When he learned to cut a punch by secretly watching the Caslons, Caslon II struck him and threatened him with prison. He and Thomas Cottrell were discharged by Caslon and established their own foundry (1757); Jackson probably cut the first types, including large poster types. He established his own foundry c.1765, cutting excellent romans, italics, and non-Latins, and later commissioning freelance punchcutters. Caslon III bought the foundry on Jackson's death, but the foreman Figgins set up on his own and retained much of the foundry's patronage.
From The Oxford Companion to the Book in Oxford Reference.