“The oldest surviving decorated type, which belonged about 1700 to the Grover Foundry and has descended to [Stephenson Blake] via Fry’s and the Fann St. Foundry.” — Jaspert. Cast in one size (22p) only. Its first known use in print was in The Observator 24–28 January, 1708. It appeared in an ad, “Scriptographia.” [John A. Lane, “The Origins of Union Pearl” in: Matrix 12 (1992), pp. 125–133, via Unionpurl]
See also Sally Castle’s dissertation The Grover Foundry’s Union Pearl: the first English ornamental script (University of Reading, 2004).