Margaret Allison states that in 1911 his address was 281 Welbeck Terrace, Ashington, and that he was 20 years when he died.
Soldiers Died in the Great War states that he was born in North Seaton and enlisted in Ashington.
There are three "William Smiths" remembered in Ashington on A17.01 (A17.27) and A17.43
However, there is only one "W. Smith" or "William Smith" on A17.06, A17.08 and A17.11 so without more information it is difficult to tell which man is being remembered.