After completing his medical education, Clayton first practiced from his father's address, 3, Percy Street, off Bedford Square. In 1842 he was elected, like his father, a Fellow of the Royal Medical and Chirurgical Society of London, and on 14 March 1843 read a paper to the Society concerning seventeen cases of a hacking cough which he had observed since 1841 as surgeon to the St Pancras School for Female Children, a charity school at St Pancras, London. This was published in that year's volume of Medico-Chirurgical Transactions under the title Some Account of an Hysterical Affection of the Vocal Apparatus, with several cases. On 13 October 1853 Clayton was elected a Fellow of the Royal College of Surgeons. He was still at the Percy Street address in 1859, but most of his later years in practice were spent at Number 5, Harley Street. In his middle years he became a "fashionable" society doctor and was the personal physician of two of the sons of Queen Victoria. In 1868, he was appointed as Extra Surgeon-in-Ordinary to the Prince of Wales, later King Edward VII, and Surgeon-in-Ordinary to his brother, Prince Alfred, Duke of Edinburgh. This caused the Medical Press and Circular to comment acidly: Despite the misgivings of the medical press, in 1872 the Prince of Wales fell sick at Scarborough with typhoid fever, and Clayton correctly diagnosed the illness. Clayton was always credited with the Prince's recovery. Clayton also became Surgeon to the Metropolitan Police, the London Philanthropic Society, and the charity of St George the Martyr, Southwark. His patients included Lord Randolph Churchill, who shortly after the birth of his son Winston made repeated visits to Clayton for "an undisclosed ailment". Frank Harris later claimed that this was syphilis. In 1885, under the heading A STAR IN THE MEDICAL FIRMAMENT, the Midland Medical Miscellany reported: On one occasion, after Clayton had successfully treated Princess Louise, Sir James Reid, Queen Victoria's personal physician, was angry when he heard that Clayton had given the Queen a prescription for her rheumatism. Reid wrote to William Jenner "If he begins that sort of thing, there is no saying where it may end". Clayton hastily responded to Reid to say he had not prescribed for the Queen. Towards the end of his life, while both were staying with Sydney Stern, Clayton remarked to the American writer Frederick Townsend Martin
Private life
Clayton had a house in Hertfordshire at Grove Cottage, Bushey Heath. Always one who "loved a lord", he was once heard to remark "I've been in luck to-day, I've met no less than seven !" He attended the Prince of Wales's levée at St James's Palace in May 1867, and at another levée in March, 1869, he was presented to Queen Victoria by the Lord Chamberlain, Viscount Sidney. In 1874, Vanity Fair magazine made Clayton No. 87 in its 'Men of the Day' series, publishing a caricature of him by "Ape" entitled "Fashionable Surgery". Pellegrini's original watercolour is in the National Portrait Gallery, which describes Clayton in its catalogue as "Surgeon and socialite". In 1880, in a series of sketches called "Our Doctors", Edmund Yates's magazine Time: a Monthly Miscellany published a sketch of a society doctor entitled "Mr Osric Claypole". This piece begins "Gold-rimmed spectacles; hair carefully distributed by the brush... a rosy, healthy face... When Osric Claypole dines out, which he does on every night that he does not entertain at home, he shuffles off the last remnant of the doctoral coil, and is the heartiest and merriest of companions." The sketch also referred to Claypole's "patients of the upper thousand of the upper ten". A few weeks later, The Academy, reviewing the sketch in Time, commented that "Mr. Osric Claypole, with his Louis Seize furniture, his Sèvres, and his "younger Court", might have figured at once in the World as a social "Celebrity at Home". Why not "Mr. Oscar Clayton in Harley Street"?" In 1890 a portrait of Clayton was painted by Frederick Goodall and exhibited at the Royal Academy. Now in the Hunterian Gallery in Glasgow, this was described in the art journal The Academy: In his diary for 30 November 1882, the day Clayton was knighted, Lewis Harcourt wrote "Several people went down on the same train to be knighted, among them Oscar Clayton, who is nominally doctor, but really "pimp" to the Prince of Wales". In a book of memoirs published in 1909, the former actress Lady Bancroft wrote – Clayton died on 27 January 1892. After the probate of his Will, he left more than £150,000, a very substantial fortune in the 1890s.
