Sir Walter, with his 61 years of life, although he never wrote a novel until he was over 40, had, fortunately for the world, a longer working career than most of his brethren.

He had maintained a platonic relationship with Jean while his first wife was still alive out of loyalty to her. A sequel to A Study in Scarlet was commissioned and The Sign of the Four appeared in Lippincott's Magazine in February 1890 under agreement with the Ward Lock company. Conan Doyle fathered five children.

He was a prolific writer whose other works include fantasy and science fiction stories plays romances poetry non-fiction and historical novels.