Regarding my own post above - I spoke too soon. The wind moved the sign and it became clear the metal band was just a token - the masonry nails hammered in at different heights showed that they had learned nothing from previous feedback.

Oh well... I have sent a mail to the enforcement team, but I'm not hopeful there's anything that can be done. The estate agent whose name is on the board says it's all down to the sign company who are nothing to do with them. And the sign company don't really know me from Adam.