After being removed from the clerkship in 1648 by the Puritan visitors (who had taken charge of the university during the English Commonwealth), he was given a scholarship at Jesus College, Oxford later the same year and received his Bachelor of Arts degree in 1649.
In his memoirs, An Afflicted Man's Testimony Concerning his Troubles (1691), he said that he had been promised a Fellowship but that this was denied because of his views on the rule of Oliver Cromwell.
He left Oxford and, whatever his views might have been, he then became a preacher in Wales under the auspices of the approvers of the Act for the Better Propagation of the Gospel, and was given the sinecure living of Llanrhaeadr-ym-Mochnant in 1653.
[2] He separated from his wife in 1666 and moved firstly to Oxford and then to London, where he published the works that made him a major figure in the literary history of Welsh Puritanism.
In 1672, he was licensed as a general preacher in Oswestry, Shropshire but returned to London in 1675, where he helped to print Welsh religious books, both reprints of earlier translations and new editions of more recent works by leading writers, and also the 1677–78 edition of the Welsh Bible.