Oh right. Not all black hat units do the Patrols, so I never thought of that.
Actually, ALL the Army did Patrols in the day. It was "Walking Out Dress" in the Mess and also often worn by the Duty Officer.
Some Reserve Units have been using it for years as Mess Kit.
I have a friend who, in the past couple of years, has used his 'points' to order it through Logistik, for Mess Dinner and other Mess functions.
Looks like it is making a comeback.