This is Royal Aero Club Certificate No.7025 issued to 2/Lt. Walter Charles Leslie Matthews, 5th Royal Fusiliers, on August 25, 1918.  Matthews was born in London on January 7, 1895.  He transferred from 5th Fusiliers to No. 125 Squadron where he piloted AirCo DH6s on anti-submarine patrols from Aldeburgh in Suffolk.  125's airfield is also given as Fowlmere from March 1 to August 17, 1918.    His records at RAF Hendon give this chronology:
 

14 February 1918  from Reading to 125 Squadron Fowlmere 
.......................       attached School of Aeronautics 
20 April 1918         from S. of A. to 125 Squadron
5 September 1918  "Not to fly above 5000 ft. 
                               Recommended for employment on .... Submarine Work." 
24 November 1918 from 31 T.D.S. to Eastern General Hospital
1 December 1918    from 31 T.D.S  to G.N.E.O.P. Instructor in Aviation
11 December 1918  from G.N.E.O.P. to 31 T.D.S. Under Instruction
31 January 1919      from 31 T.D.S. to Crystal Palace

His record also says his appointment as a 2nd Lieutenant was published in the London Gazette N.R. 379 7/11/18.