Trefor, it seems we are thinking about a different picture.
The one I have in mind is a formal group of regimental officers , seated, with Her Majesty in the middle. On her right (left as you look at the picture) is a young subaltern who has forgotten to push his sporran down between his knees, revealing the obvious, all the while with a silly grin on his face.
The picture you have in mind is more in keeping with a sergeant-major's behaviour!
Regards,
Mike