From "the Doctor and the Detective," by Martin Booth:

The success was not all Conan Doyle's, however. Part of the achievement has to be put down to Newnes's decision that every page of the Strand Magazine had to carry an illustration. The Sherlock Holmes stories, therefore, had to have an artist seconded to them who would illustrate all the stories consistently. The artist chosen by Greenhough Smith and the art editor, W.H.J. Boot, was Sidney Paget, born in 1860 and a student of the Royal Academy School. He was, in fact appointed in error. Boot had wanted Walter Paget, Sidney's brother who was an illustrator for the Illustrated London News and had ahead done the drawings for Sir H. Rider Haggard's King Solomon's Mines and She as well as Robert Louis Stevenson's Treasure Island. However, an invitation was sent by mistake to Sidney Paget at his studio at 1 Holland Park Road, Kensington.

In all, Sidney Paget provided 357 drawings for the Sherlock Holmes stories, having his brother, Walter, sit for the character. A tall, elegant man, Walter Paget was to regret accepting the task, for he was not infrequently accosted in the street as Sherlock Holmes. Such was the effect of Sidney Paget's authoritative style and the vast readership that stories received that one anecdote has Walter Paget attending Covent Garden opera house when a woman pointed him out and yelled 'There goes Sherlock Holmes!' which caused him to spend the entire performance hunched in his seat.

Watson was most likely modeled upon an old art school acquaintance of Paget's called Alfred Morr Butler, who became an eminent architect.

Conan Doyle approved of Sidney Paget's strong line drawings which so appropriately complemented the stories. His appreciation was shown in June 1893, when he sent Paget a silver cigarette case as a wedding present. It was engraved 'from Sherlock Holmes'. In actual fact, Paget drew a character which was not that much like Conan Doyle's original visual idea. Paget's Holmes was more handsome. Conan Doyle had envisaged an ugly man with a thin, angular face, a hooked nose and two small eyes set close together. In stature, he was tall but also cadaverous. Paget's beautification of Holmes paid dividends. Women were attracted to his austere looks whilst men sought to emulate his style of tailoring.

Paget was also responsible for one of Holmes's most famous attribute. In “The Boscombe Valley Mystery,” Conan Doyle dressed Holmes in 'long grey traveling cloak and close-fitting cloth cap', but Paget changed this into a hooded coat and deerstalker hat such as he wore himself when in the country. The image stuck, to be reinforced ever since by every actor who had ever played the part.

Until his death in January 1908, Paget drew every Sherlock Holmes illustration to appear in the Strand Magazine. After his death, Conan Doyle chose Arthur Twiddle as his replacement. He had already illustrated one of the Holmes books and Conan Doyle's novel Sir Nigel. One story, however, entitled 'The Adventure of the Dying Detective', was illustrated by Walter Paget, in the December 1913 issue of the magazine. In 1914, Frank Wiles illustrated all nine installments of ‘The Valley of Fear’ in addition to three of the last Sherlock Holmes stories. In America, Frederick Dorr Steele was commissioned to illustrate the Holmes books, giving a different interpretation of how the great detective looked. Yet the illustration that has stuck in the public consciousness is Paget's picture of an elegant aesthete, the true and lasting figure of Sherlock Holmes on the page.