It is a BA flight. The reason why I’ve confused everyone is because I flew PHX-LHR after the cancellation. It was so stressful, I’ve forgotten where I’ve come from. Ha! Thanks everyone for your quick replies. The flight attendant has confirmed that this PHX flight does switch off landing at 3 and 5 and today we land at 3. I will take the bus to 5 and visit the lounge there. Thank you everyone! I really appreciate this community!