Well...I may be able to give you some more int on the photo...
As he won a cup for cooking...and looking at the group in No1s (patrol dress) I would say he was the Officers Mess Steward. Until the privatisation of the mess servants, the officers mess was run by a Sgt with a Cpl (or L/Cpl) and some private soldiers.
The two chaps at the rear in either mess dress or evening wear (the front row heads obscure any NCO rank would appear to confirm this idea...
To my regret I cant make out the collar dogs nor his medal ribbons...The collars look like a laurel wreath surmounted by a crown with a cross in the middle....Almost A QA cap badge!!!

But not....
