Source: Record of promotion in service records of Robert Swansborough, 745172.
Find-A-Grave
May have joined under aged.
Family Search: When Wilbert Ernest King was born in August 1898, in Percy Township, Northumberland, Ontario, Canada, his father, Thomas King, was 31 and his mother, Jennet Scott, was 20. He married Mary Kathleen MacDonald on 22 November 1922, in Wellington, Prince Edward, Ontario, Canada. He lived in Peterborough, Ontario, Canada for about 10 years and Wellington, Ontario, Canada in 1921. He registered for military service in 1916. In 1916, at the age of 18, his occupation is listed as farmer in Norwood, Asphodel, Peterborough, Ontario, Canada.
War Diary of the 18th Battalion CEF 