 Dashwood was returned unopposed as Member of Parliament for Winchelsea at the 1708 British general election.There was confusion about Dashwood's political inclinations, but he acted as a Whig in voting for the naturalization of the Palatines in February 1709, and supporting the impeachment of Dr Sacheverell in 1710.He also signed an address of the London lieutenancy attacking outrages committed by High Church mobs.