Last time I tried that at the AMS lounge it turned out the agent was English! Getting to the lounge is such a trek I wouldn't worry about it, and you have the LGW facility to look forward to.

The online rules are the oneworld ones (which definitely does not cover your scenario) and a very simplistic set of statements in Manage My Booking and on ba.com - the latter basically saying you need to be in Club Europe / World or holding status, without much context. To the best of my knowledge there isn't a more comprehensive set of BA guidelines on public view, other than the unofficial ones on Flyertalk.