Gerard’s grandfather, a younger brother of the Elizabethan master of the rolls, founded the Middlesex branch of the family. Gerard’s own marriage took him into the heart of the puritan cousinage. He was a prominent Parliamentarian in the Civil War, serving as treasurer at war. A ‘fierce Presbyterian’, he was imprisoned at Pride’s Purge and took no part in politics during the Interregnum, though he was summoned to Cromwell’s ‘Other House’. On the return of the secluded Members he was restored to his post as chancellor of the duchy, and took part in the meetings of the Presbyterian cabal at Suffolk House.
In the general election of 1660 Gerard stood unsuccessfully for Middlesex but was returned for Lancaster, presumably on the duchy interest. His two sons, Francis and Gilbert, also sat in the Convention, in which he was an active but not particularly prominent Member, being named to 49 committees, and acting as teller in two divisions. He made seven recorded speeches. He was on the committees for the abolition of the court of wards, the King’s reception, the indemnity bill and the confirmation of parliamentary privilege. He was among those charged with preparing instructions for the messengers to the King, and was made a commissioner for administering the oath of allegiance to Members on 4 June. His name stands first on the list of the committee to inquire into the publication of Anglican pamphlets on 30 June. In the grand committee on religion he said ‘he could not give his vote to the question until he heard whether it were against the Covenant’. He was also named to the committees for settlement of the revenue and consideration of the Lords’ amendments to the pardon bill. On 22 Aug. he said that he had invited several persons to surrender themselves on the proclamation, and could never give his vote to except them for life. Gerard had already been removed from office, and played little part in the second session of the Convention. On its dissolution, he retired into private life, though he was nominated to the knighthood of the Royal Oak, with an estate of £600 p.a. He died on 6 Jan. 1670 and was buried at Harrow.