Career
Soon after Petre inherited his title, James II same to the throne. In 1688, Thomas was appointed Lord Lieutenant of Essex and custos rotulorum for Essex. After James"s flight in the Glorious Revolution, Petre was forced to resign when the militia refused to serve a Catholic.
After the Revolution, much of the vast revenues from the Petre estates was sent abroad to help maintain those institutions in the continental Europe that provided education for Catholic Englishmen.
Thomas married Mary Clifton (died 1706), daughter of Sir Thomas Clifton, Bt of Lytham, Lancashire. He also had a daughter Mary Petre, (1693–1713).