Google shows theres a picture of the grave at
https://sites.google.com/site/ourher...l-rd-graveyard
Died 5th November, 1918
Missed the Armistice by six days
To quote from that site
"Son of Wesley and Margaret Sterling, 68, Newport St., Belfast.
Living at No 5 Loftus Street, Belfast in 1911 Irish census. Walter was aged 7.
This was the verse his Mother and Father placed in the Belfast newspaper.
In fond and loving memory of our dear son No 310462 Pte Walter Ambrose Sterling, R.A.F. aged 14 years and 7 months, who departed this life on 5th November, 1918, at Blandford Camp Hospital, Dorset, and was interred in Shankill Burying ground, Belfast."
The guess about the 'flu could be right
see
Blandford Camp
"By the middle of 1918 part of the barracks was taken over by the newly-formed Royal Air Force which had been formed on 1st April of that year.
In 1918 the influenza pandemic caused the deaths of several German prisoners held in Blandford P.O.W.Camp......."
So there was an outbreak there that year, and we know it was the young and fit who seemed to get hit most by that version of the 'flu