 He was returned as the Member of Parliament for Aldeburgh at the 1747 election on the interest of his brother, Thomas Fonnereau, who had developed an independent interest in the borough at the expense of the Government (which had formerly controlled it by patronage).However, Zachary consistently voted in support of Government when in Parliament.By his marriage to Margaret Martyn, he left five children, two of whom also served as Members of Parliament for Aldeburgh