HI
I'll throw in what I know...........
I know a chap who was an Armoured MWO and qualified "Master Gunner" proper. He
never worn anything on the cuff of his DEU tunic other than his rank. Let's just say that he was exactly the type of guy who would have worn something (like this bullion described above) if he was permitted to. However, he was Army enough (and honestly professional enough) to know not to wear something not permitted to wear also.
I also know that every year on the Royal Canadian Dragoon parade honouring our three Boer War VCs won in the action at Leliefontein, the Arty guys from the RCHA come over, in period dress, and pull one of the actual 12pdrs "saved" in that action, across in front of the Regiment. Not a requirement, mind you, but rather done willingly by them for us. I always thought it pretty cool for them to do that. Then on St Barbara's Day, we go pull their duties so they can go get pissed!!!
Besides............
ALL Armoured Gunners are "Master" gunners!!!
regards
Darrell