Spot on with your observations Phil
As I understand it there was only ever one commando title that had a black back, which was a 2 piece contruction like conventional WW2 printed titles, such as this example:
http://www.brittonsbadges.co.uk/viewphoto.php?x=0
A pair of the 12s has surfaced but are being correctly descrided as repro:
https://www.ebay.co.uk/itm/232929334878?ul_noapp=true