Joan is the middle child of Harold and Sarah Watson. She was preceded by three years by Harold "Harry" Watson Jr., and followed two years later by Lucy Watson.
The timeline of events leading up to and including the stories of the Ladies of Baker Street.
Watson tried for eight years to get admittance to medical school. When her father's alma mater refused her, she focused on local institutions, since they were living in London by then. The events of the Surgeons' Hall riot also influenced her switch regarding institutions. (The change is how she missed out on being one of the early members of the Edinburgh Seven). Eventually, she gave up attempting to achieve the training and licensing in the traditional manner.
The Medical Act of 1876 repealed the Medical Act of 1860 and allowed qualified women to be licensed as medical practitioners. Queen Victoria did not agree with the act in concept, but provided her assent anyway.
Watson was injured during the Battle of Mainwand on 27th July, 1880, taking a Jezail bullet to the shoulder. She avoided capture by the enemy only because her orderly, Murray, dragged her out of danger. She was unconscious at the time of recovery and thus was incapable of preventing those who tended to her from discovering that she was not, in fact, Harry Watson, and she was swiftly discharged from the service not long after.