According to the family he was in the Royal Flying Corps but - 
Joined Royal Navy Air Service on 18th birthday : F47681 / 50373 or 56373
Assigned to Presdident II (admin office in London) then Tregantle (RNAS storage in Cornwall)
Transferred to RAF on 31 March 1918.
RFC and RNAS merged to become RAF on 1 Apr 1918.
In later life was the Librarian at Cranfield Airfield in Lincolnshire.
RAF Service Date 20 Mar 1918, Service Number (247681) (from Ancestry index of RAF Service records).
  

ADM/188/639
FG47681
Date of Birth : 20 March 1900 (The date is not clear but ONS search confirms as 1900)
Place of Birth : Worcester
Occupation : Moror Mechi (Mechanic)
Date and Period of Engagements - 20 March 1918 - 4+4 years
Age : Appears to say 16 but not clear
Height : 5ft 1 1/4in
Chest : 35 in
Hair : Brn 
Eyes : Blue
Complexion : Fresh
No wounds, scars or marks listed
Ships etc served in:
President II this was an Administration office in London
List : 1415
No : 50373 ?
Rating : ?
From : ?
To : ?
Rating :4 3
Tregantle  A Royal Naval Air Service store in Cornwall. Used for training crafts.
List, No and Rating as above.
From : ?
To : 31 March 1918
Where discharged : R.A.F.
Character : vg (very good>