Petty’s ancestors were yeomen farmers: his great-grandfather, also Maximilian, purchased Tetsworth manor, Oxfordshire, and other properties in neighbouring Stoke Talmage during the reign of Henry VIII. The family’s rise to gentle status was confirmed by a grant of arms in the 1570s.
Petty’s political sympathies may be inferred from his second marriage, to the daughter of Sir Richard Ingoldsby, a kinsman of Oliver Cromwell* and John Hampden*. However, he was returned to the Commons for Westbury in 1628 on the interest of his brother-in-law Sir James Ley*, who controlled the borough. He is not recorded to have made any contribution to the work of the House.
Little has been discovered of Petty outside Parliament. In 1634 he was cited for failing to register his arms with the heralds, although he had earlier encouraged his kinsman Anthony Wood to do so.
