Oxenos, of course the other sign was the wide spacing between the two rings.
Brian, I believe the Army had the equivalent of green shield. The story went something like this:
Newly posted officer, straight from Sandhurst, arriving at his regiment.
CO in loud voice "You there", or words to that effect, "what's that on your shoulder?"
NPO looks at shoulder expecting to see bird poo but only sees 3 shiney pips, " my rank, Sir."
"Get them off, you're a subaltern until I tell you otherwise."
True or not, probably a sensible thing
A chief would help a fg off JENGO but expect a flt lt to know his stuff.