I agree with those that have highlighted how bad priority boarding is now being handled - too many in the line (I assume because of the inclusion of Ruby/Bronze CHs), and I do believe that those flying in First and Business should get priority over GCHs.
However, my major gripe is that BA needs to practice what it preaches! Happy BA customers are happy as a result of:
predictability (i.e. you know what you're going to get) and
consistency (i.e. the service is always the same), and that also means their priority boarding policy needs to be policed - people should be turned back if they try to board early.
[Customers are also made happy when they get upgraded but let's put that one on one side!
]
And to be honest I don't know why BA find it so difficult to deliver a predictable and consistent service when it comes to priority boarding. Just stick to a priority boarding policy and make sure your gate staff use it.