I was on the BA123 LHR-Doha last week, original seat was 5A, then magically moved to 1A, so I assumed FLUB at 72-hours out. Checked in, still in 1A but as I was connecting to a QR flight, needed to collect a boarding pass, that's when I found out I'd been moved to 6K. According to the crew, which were LGW based, and brilliant, the flight was showing as full in club, then wasn't, so I would have been a billy no mates if left in FLUB, and automatically moved to the smaller CS cabin