Robert Petre, 3rd Baron Petre English Baron (1599–1638) Parents William Petre, 2nd Baron Petre Lady Katherine Somerset Children John Petre, 5th Baron Petre William Petre, 4th Baron Petre Thomas Petre, 6th Baron Petre Mary Petre Siblings John Petre Elisabeth Petre Mary Petre William Petre Catherine Petre Partners Mary Browne