In February 1679, Erle was returned unopposed as a Member of Parliament (MP) for Wareham (a pocket borough controlled by his family) into the first Exclusion Parliament. He voted for exclusion. At the second general election in 1679, Erle was again returned unopposed, but left no record in the second Exclusion Parliament. He was returned unopposed again at the 1681 English general election but was again inactive. At the 1685 English general election Erle was returned unopposed again, and was named to committees in Parliament but was called away in response to Monmouth's invasion. On 27 May 1685, he was made Deputy Lieutenant of Dorset. Erle took command of the East Dorset militia as major, and fought as a volunteer at the Battle of Sedgemoor with his friend Thomas Chafin. Subsequently, he was presented to the King by Lord Churchill but received a cold reception from James II.