He acquired a reputation in his profession, more especially as a man-midwife, and on the petition of his father he obtained, in February 1673, the reversion of Sir John Hinton's place as physician in ordinary to the king.
[1] In March 1688 the Royal College of Physicians, on the information of Walter Charleton, took action against Chamberlen for the "illegal and evil" practice of medicine.
He continued, however, to enjoy an extensive business at court, while he was selected by James II to attend Mary of Modena in her confinements.
At the birth of Prince James Francis Edward Stuart, on 10 June 1688, Chamberlen came too late to be present.
He parted with the family secret of the midwifery forceps to the Dutch surgeon Hendrik van Roonhuisen.
[1] In 1685 Chamberlen published Manuale Medicum: or a small Treatise of the Art of Physick in general and of Vomits and the Jesuits Powder in particular, London, 1685.
[4] It added little to the Manuale Medicum, but touched on preventive medicine with A Proposal for the better securing, of health, intended in the year 1689 and still ready to be humbly offered to the Consideration of the Honourable Houses of Parliament.
Two years later the project was revived in a modified form; and bill passed both houses and received the royal assent on 27 April 1696.
In 1700 he was urging the latest version of his land bank scheme on the Parliament of Scotland, in a pamphlet A Few Proposals humbly recommending .... the Establishing a Land-Credit in this Kingdom.