Yeah, different rules at different out-stations I'm afraid. Some places are set up for it, others are not. The maddening ones are the Iberia handling agents in Spain - some airports will do AUP, others haven't had the training, or the staff grade is set to a basic level, and therefore the staff can't do it. And this is the same company as BA.

Consequently it's easy at some places, impossible at others. So in Venice and Malpensa they will actively try to sell you an upgrade, Linate can't do it. Geneva will only do longhauls, not CE upgrades, Nice wasn't a problem until the staff were outsourced a few months ago, Turin can do it if the right agent is on duty, and so it goes on.