He was successful in practice, with occasional disappointments, as when a man complained in 1573 that the cure of his wife was a failure and got twenty shillings damages from Clowes.

[1] After this war Clowes returned to London, and on 18 July 1588 was admitted an assistant on the court of the Barber-Surgeons' Company, and immediately after served in the fleet which defeated the Spanish Armada.

He kept his military surgical chest by him, with the bear and ragged staff of his old commander on the lid, but was never called to serve in war again, and after being appointed surgeon to the queen, and spending several years in successful practice in London, retired to a country house at Plaistow in Essex.

He succeeded in handing on some court influence to his son William Clowes the younger, who was made surgeon to Henry Frederick, Prince of Wales a few years after his father's death.

But he trusted to his own observation, and a spirit of inquiry pervades his pages which makes them altogether different from the compilations from authorities which are to be found in the surgical works of his contemporaries Baker and Banester.

He was called to a northern clothier whose leg was broken by robbers two miles outside London; to another man whose injury was received by the breaking down of a gallery at a bear-baiting; another patient was a serving-man whose leg had been pierced by an arrow as he walked near the butts; a fifth was one of Sir Francis Drake's sailors who had been shot by a poisoned arrow on the coast of Brazil; a sixth was a merchant wounded on his own ship by a pirate at the mouth of the Thames.

[1] He did not conceal that he had secret remedies — 'my unguent,’ 'my balm,’ 'of my collection' — but he never made bargains for cures, and never touted for patients as some surgeons did at that time.

He figures a barber's basin among his instruments of surgery, and says he was a good embalmer of dead bodies, and knew well from practice how to roll cerecloths[1] Besides ready colloquial English, he shows a wide acquaintance with proverbs, and a fair knowledge of French and of Latin.