Announced and enforced at LHR for Rome today.
Although she didn't help herself by announcing 'Golds and OneWorld Silvers' - she did correct it with a manual 'shout' when the first silver got turned away with 'Golds and Emeralds only'.
Seemed to make life smoother.
No one intercepted me with a yellow tag (two people manning regular track security - no one on fast track) and she didn't mention it on boarding - but there were plenty of tags in evidence.
A good amount of cabin baggage shuffling going on toward the end - but it all fitted - just some stuff was a few rows away from the owner.