This topic might have a better name.
If the book explicitly uses John Smith of Grothill as his name, the best way of disambiguating is by using that as the page title.
Talk about it here.
Sir John Smith of Grothill was the Lord Provost of Edinburgh in 1645.
He was infected with the bubonic plague, and also had a Grief Leech attached to his stomach. The leech was removed by the Twelfth Doctor who then cured Smith with a tablet from the TARDIS.
He later led the people of Edinburgh in defeating the Grief Leeches with the help of the Doctor and his companions. (PROSE: Plague City)