Career
Born about 1672, Haynes entered the service of the Mint as weigher and teller in 1696 or early in 1697, almost at the same time as Isaac Newton"s appointment as Warden. He was promoted to be assay-master in 1723. Haynes was close to Newton, who died in 1727.
In April 1737, after forty years in the Mint, Haynes was allowed to appoint a deputy.
He retired on full pension, 8 February 1749, retaining the auditorship of the tally office in the exchequer. Richard Baron described Haynes as a Unitarian.
Haynes died at Queen Square, Westminster, on 19 November 1749, aged 77.