A couple of bits of info about the photo:
The original caption in "The War Illustrated" (Vol 5 Issue No 121) was ;
"ROYAL OBSERVER CORPS member wearing the new battle dress of blue-grey serge. A woven circular badge , as shown above , is worn on the left breast. The blue beret bears the R.O.C. metal badge.
Photo, Associated Press
Online copy here.
A modern digitalised copy of the photo is on the AP website with the "creation date : January 26, 1942 03:00:00 AM
WWII ENGLAND ROYAL OBSERVER CORPS
Also found diagram for positioning of insignia/badges which notes;
"Center of spitfire badge should be
midway between the shoulder seam and elbow"
Badge in photo seems to be lower
Question - The Master Test badge was worn on both arms (which is no problem for 'plan' view badge ) but would the badge in original post be one of a 'matching set'.