He was appointed by the royally chartered proprietor of Maryland, Charles Calvert, 3rd Baron Baltimore (1637–1715), as a caretaker to replace Lt. Gen Josias Fendall (1628–1682), the fifth/sixth?

Charles Calvert (1688–1734), illegitimate son of the Proprietor, was made Governor, and Philip was appointed Deputy-Lieutenant and Councillor of the Province.

[1] In 1990, the bodies of Phillip Calvert, Anne Wolsely Calvert, and the infant were found in lead coffins in a brick vault located in the ruins of a brick chapel in the "Chapel Field" in St. Mary's City, Maryland, the former colonial capital.

Examination of these remains provided scientists and historians with significant insight regarding life in 17th century Maryland.

[3] The baby is assessed to have died about three months after his father, in the spring of 1683, judging by the pine and oak pollen in the coffin.