John, 5th Baron Petre, seems never to have lived at Thorndon Hall, usually considered the main Petre residence. He lived instead with his mother at Ingatestone. He was in poor health for many years, and the terms of a will made in 1677 make it clear that he believed his mother would outlive him.3 Essex RO, D/DP/F77. She died on 13 Jan. 1685, just days before her son.4 Ibid. D/DDP/L41/75. His health and Catholicism would probably have precluded him from taking his seat in the Lords, but in the event no Parliament was held during his short tenure of the barony. He died unmarried, and his bequests suggest that his closest relationships were within his immediate family. During the year that he held the title, he received over £6,000 from the Petre estates. He used this to meet the obligations of the estate, including payments towards ‘the growing interest’ on the debts contracted by his brother, William Petre, 4th Baron Petre. He was also able to pay £3,000 towards redeeming those debts.5 Ibid. D/DP/F81.