All, E. Tompion is not to be confused with Thomas Tompion "The Father of English Watchmakers"...Per
Wikisource the later "died on 20 Nov. 1713, and was buried in Westminster Abbey. In the same grave, thirty-eight years later, George Graham, Tompion's favourite pupil and nephew by marriage, was laid. By his will, dated 21 Oct. and proved 27 Nov. 1713, Tompion, who was
apparently a bachelor, left his houses, land, &c., at Ickwell in the parish of Northhill to his nephew Thomas, son of his brother James. There are legacies to a niece, wife of Edward Banger (
who carried on business as a watchmaker with the younger Thomas Tompion), and a great-niece, but the bulk of the property was left to George Graham and his wife Elizabeth, daughter of Tompion's brother James.
Perhaps E. Tompion is related to one or more of these people...