This is the William who married in Sunderland in the 1911 census. Note his p o b .
https://www.familysearch.org/ark:/61903/1:1:XWWR-NK3There is something about this chap that I feel does not add up! He often seems to be going under the double barrelled name Wellesley - McKown. I just did a search on the newspaper archive for the name Wellesley - McKown. It produced 15 hits. Three of these were from 1896 where a W A Wellesley McKown seemed to be involved in the sale of a hotel in Oban. The remaining 12 are all from 1910 and consistently refer to W A Wellesley - McKown, BSc but he seems to have been at the same time as being a "petroleum expert" the manager of Richmond Ice Rink. The location ties up with the 1911 census.
The cemetery record for him shows a further twist. His occupation on that is given as Doctor of Medicine.
https://www.familysearch.org/ark:/61903/3:1:3Q9M-CS6T-N9LR-J?i=844&cat=825520This is also shown in his death notice in the Sunderland Echo 5 Feb 1920.
Wellesley - McKown 140 Roker Avenue ( at the residence of his parents in law ) Feb 5th 1920 Dr. W A Wellesley- McKown BSc FCS, the beloved husband of Eveline Wellesley - McKown (nee Roebuck).
So could he be your man?
On a different tack you might find it of interest to have a look at the service record of James Thomas ( there is only one record for James Thomas b Scotland 1822!). On the last page there is a note naming W McKown.
William
