He became a fellow of the Royal College of Physicians in 1851, and filled almost every post of honour it could offer, except the presidency, in the contest for which he was beaten by Sir Andrew Clark in 1888.

[5] Quain was the author of several memoirs, dealing for the most part with disorders of the heart, but his name will be best remembered by the Dictionary of Medicine, the preparation of which occupied him from 1875 to 1882 (2nd edition, 1894; 3rd, 1902).

Quain was very prominent in affairs of medicine, being a censor and council member of the Royal College of Physicians and was narrowly defeated by Sir Andrew Clark in 1888 in the election for the position of president.

He was active on many committees but probably the most important of these contributions was the Royal Commission to enquire into the nature and causes and methods of prevention of cattle plague.

This commission included a number of famous people such as Henry Bence Jones (1813–1873) and Edmond Alexander Parkes (1819–1876).

Quain vehemently sided with the section that wanted the extermination of the plague at any price and was opposed in this by a number of the members of the commission, including Bence Jones.

Quain's work and particularly letters he wrote to newspapers and magazines turned the tide and the recommendations to exterminate were carried out with success.

Quain was regarded universally as a fine physician, but apparently achieved his results by intuition and instinct rather than by analysis of the patient's problems.

Quain's renown as a physician was due not only to the sound commonsense that he brought to bear in diagnosis, but also to the good-humoured geniality that he showed to patients and friends, He was famous for his epigrammatic quotes, and regarded as a fine raconteur and club member of the Garrick and Athenaeum, his broad Irish accent adding colour to the stories he told.