I already mentioned this on an other thread, but just briefly, on a return from IST>LHR we had 1A&C booked for many months in CE. Day before we mysteriously got moved to Row 7. To cut a long story short the Man who got our seats (with one blocked) was a Premier/VIP (Black Icon on the iPad). We were both Gold.
Actually, in a situation like this then yes, the whole cabin should move back one row in my opinion! No one is Row 2-6 is really going to be bothered a 1 Row change. Whereas us moving back 6 Rows was actually quite annoying! We got 5,000 SR each anyhow after complaining.