Amex is talking about mainline BA, and 'old' contract at that. New entrant cabin crew would be hard pushed to earn this much, especially at EuroGatwick or Cityflyer.
The Portugal based crew are employed by GB Airways, which is one of the BA franchises. I don't know about their salaries, but I'm sure if you wrote to Cabin Crew Recruitment at GB HQ at The Beehive, LGW they will have info for you.
Good luck,
D1L