Robert Edward Petre, 9th Baron Petre was a British peer and prominent member of the English Roman Catholic nobility. He hailed from an extraordinarily affluent family and devoted himself to philanthropic endeavors. Lord Petre played a crucial role in commissioning James Paine to design a new Thorndon Hall as well as a house in Mayfair.

Ingatestone Hall is a Grade I listed 16th-century manor house in Essex, England. It is located outside the village of Ingatestone, approximately 5 miles (8.0 km) south west of Chelmsford and 25 miles (40 km) north east of London. The house was built by Sir William Petre, and his descendants live in the house to this day. Part of the house is leased out as offices while the current Lord Petre's son and heir apparent lives in a private wing with his family. The Hall formerly housed Tudor monarchs such as Queen Elizabeth I.