He married the daughter of Dr. Peter Heylyn at Abingdon, and afterwards purchased the perpetual advowson of the living of Waddington, near Lincoln, which he held for some time, together with that of Gedney, also in Lincolnshire.
Barnard was the author of a pamphlet in three sheets quarto, entitled Censura Cleri, against scandalous ministers not fit to be restored to the church's livings in prudence, piety, and fame.
This was published in the latter end of 1659 or beginning of 1660, ‘to prevent such from being restored to their livings as had been ejected by the godly party in 1654–55.’ His name is not set to this pamphlet, and Anthony a Wood says he did not care afterwards, when he saw how the event proved, to be known as its author.
He is best known as the author of Theologo-Historicus, a true life of the most reverend divine and excellent historian, Peter Heylyn, D.D., sub-dean of Windsor (London, 1683, 8vo).
This was published, according to the author, to correct the errors, supply the defects, and confute the calumnies of George Vernon, M.A., rector of Burton in Gloucester, who had brought out a life of Dr. Heylyn in 1682.