Just to welcome you to Flyertalk and welcome you to the BA forum pboniface. No shortage of greetings in this forum at least. That indeed is a long stretch without a Gold greeting. Perhaps some of them have been the subtle version where you are spoken to consistently by name rather than "Sir" or "Madam". On shorter sectors it isn't realistic (and you won't get it on Cathay on PEK-HKG on a Friday afternoon either). On a longer sector I would hope you get some acknowledgement at some point.