I for one am a little tired of those neverending announcments that I if I need any assistance "please contact one of our OW Alliance partners".

This is completely and utterly meaningless. Not only that that, but it is completely misleading to tell people that another airline's representatives will help with anything, when clearly they will (and can) not.

Do BA crew members realise what a nonsense this is?

I challenge anyone to give me one, yay one, example of a OW airline's ground staff helping with an issue afer a BA flight.