He married Elizabeth Pride, great-niece and ward of George Monck, 1st Duke of Albemarle, whose heir-at-law she eventually became, and there exists a pedigree of the Moncks of Potheridge engraved by Sherwin expressly to show his wife's claim to that position.
These comprise large plates of Charles II, Catherine of Braganza, Prince Rupert, Baron Gerard of Brandon, the Duchess of Cleveland, and Slingsby Bethel.
He engraved the title to John Reynolds's ‘Triumphes of God's Revenge against Murder,’ 1670, several of the plates in Francis Sandford's History of the Coronation of James II, 1687, and the portraits of Dr. William Sermon, prefixed to his works.
Sherwin was one of the early practitioners of mezzotint, a technique he learned from Prince Rupert.
He dedicated to the Prince a pair of large portraits of Charles II and his queen engraved using the method; the former of these is dated 1669, the earliest found on an English mezzotint.