Mercer’s father, who like his son was probably a linen draper, served as bailiff of Northampton in 1568 and mayor in 1583.
In the first session Mercer was appointed to three bill committees, of which the first was to consider the ecclesiastical grievances outlined by the Northamptonshire Member Sir Edward Montagu (23 Mar. 1604).
Mercer does not seem to have stood for Parliament again. He was chosen mayor for a third time in 1612, and was given leave to erect a small house in the churchyard of St. Katharine’s.
