On his return to Britain, he became Physician to St Thomas' Hospital (1783–1795), Physician Extraordinary to the Prince of Wales (1786) and Physician in Ordinary to the King (George IV and William IV). He was a founder member of the Fellow of the Royal Society in 1784 and delivered their Croonian lecture in 1788 "On the Nature of the Muscles, and on the Theory of Muscular Motion". By virtue of these court and hospital appointments, he built up a good practice for himself in London, and the government constantly consulted him on questions of public hygiene. In 1795 Blane was appointed as Commissioner on the Sick and Wounded Board of the Admiralty; the provision of soap, lemons, adequate ventilation and standardised medical stores have all been attributed to his reforms. He was an instrumental advisor to the government in the drafting of the 1799 Quarantine Act. Blane left the Commission in 1802. 1809 Blane provided expert medical advice with regards to the Walcheren expedition. This involved a British occupation of Walcheren Island with 40,000 men. The island was surrounded by marshland and many troops were struck down with 'Walcheren Fever', most likely malaria. The General Staff heeded Blane's advice that the occupying forces should be evacuated due to the likelihood of sickness. In reward for his services to the Walcheren expedition and his other Naval contributions he was made baronet, of Blanefield in the County of Ayr, on 26 December 1812.