Here are some excerpts from the Arthur Conan Doyle Encyclopaedia:

Major Alfred Herbert Wood aka "Woodie" (23 april 1866 - 19 april 1941) was a school master who became friend, private secretary and business manager to Arthur Conan Doyle from 1897 to 1930.Wood was a Freemason and a bachelor, and Adrian Doyle believed him to be a prototype for Dr. Watson. While ACD himself didn’t explicitly state that, there are certain parallels. And it’s quite a curious detail that Major Wood never married.
Between 1882 an 1890, he met Arthur Conan Doyle in Southsea when Conan Doyle was practising medicine and they became close friends.
On 6-7 september 1892, he played cricket with Conan Doyle (as captain) in the cricket team The Idlers versus Norwood. Match Drawn.
In 1897, Alfred Wood became private secretary of Arthur Conan Doyle.
In may 1905, he joined the Hindhead Golf Club, where Conan Doyle was also member.
On 6 july 1906, he was present at Conan Doyle's first wife funerals. According to Georgina Doyle (Out of the Shadow, Calabash Press, 2004), Lena Jean Conan Doyle told that Wood's nephew told her that Alfred Wood felt it was easier to work as secretary under Louisa's regime than under Jean's.
Throughout the Great War he served in France in the 5th Royal Sussex Territorials, where he was Town Major of Beauquesne. He also served in Italy in 1918.
Note that Alfred H. Wood had a nephew named Sholto Wood. Bartholomew and Thaddeus Sholto were the twin sons of Major John Sholto in Arthur Conan Doyle's novel: The Sign of Four (1888).
