No longer partnered with BA
As this comes up at the top of the Google search results for "Porto Lounge BA", I think it is worth pointing out that there is no longer a lounge at Porto for BA flyers.
Found this out yesterday. They still accept people in the Iberia frequent flyer programme, but no longer BA.
It seems the BA ground staff don't know this though, as they directed us to the lounge at checkin !