Combined Operations GSO2 missing

Major D.O Couper is missing, no doubt looking at the date the Schelde area but were would it be the best to look for information, I think:

Piece reference DEFE 2/979
Combined Operations Headquaters: historical records, war diaries and record system organisation.

 

What formation was he part of Philip?

ie Bde, Div etc?

 

GSO 2 Royal Artillery

 

You'll have to forgive me..I get out of my depth when its after June 1940.

I get the GSO 2 (General Staff Officer-Intelligence (IIRC)) bit but he must have been with a formation like 3 Division of XXX Corps etc?

Edit

Just looked him up on CWGC:

CWGC :: Casualty Details

 

I know it but like you see its all CWGC gives

 

I would look in this one first:

DEFE 2/31 Combined Operations Headquarters War Diaries 1944 Nov 1-1945 Jan 7

 

thank you