[2] Proby was returned as Member of Parliament for Huntingdonshire at a by-election on 23 December 1693 on the interest of the Whig Earl of Manchester.
He supported a motion on 26 February 1702 to vindicate the Commons' for the impeachment of the Whig ministers, was not put forward by Manchester at the 1702 English general election.
[2] After six years absence, Proby was returned to Parliament on his own account as MP for Huntingdonshire at a by-election on 31 January 1708 and was re-elected at the 1708 British general election.
He stood as an independent, determined to avoid party entanglements, and voted against the impeachment of Dr Sacheverell in 1710.
He left his unmarried daughter his personal estate, valued at £10,000, together with another £5,000, to be raised by selling property at Old Weston and from rents of his other Huntingdonshire manors.