An interesting photo Mike. I cant really remember seeing any Army photos, most being the RAF as Jon has pointed out.
As a point of interest (if my eyes are seeing it right) whereas the RAF example is a small 'half moon' of cloth worn in front of or just behind the peak of the side cap, the Army photo of OCTU you've highlighted looks instead like a strip of white tape worn along the upper edge of the peak, rather than a separate piece of cloth as worn by the RAF. I may be wrong...
