I've been keeping my eye on this thread over the last while to ensure that things did not get out of hand and obviously Neil was doing the same.
To bring it back on to topic, seat changes are done for a variety of reasons which may have been correct at the time of change. Many years ago, before one could select seats on-line - or indeed book on-line, I had selected seats via my travel agent. It was in the days that long-standing V-Flyers may remember when, in the days before security tightened up, a staffer gave us the details of which specific aircraft were scheduled to fly each route ex-LHR up to two weeks in advance. We were to be on G-VHOT to SFO and were seated in what is now 20 and 21K. (The config was different because the upper deck was UC/PE before it went to all UC and then to UC/Econ) On check-in we found that our seats were changed and we were now in 21 and 22K. We were told it was because the seat was inoperable. On board I found a Japanese lady sitting in my seat because she had realised that side-by-side was better than being across the aisle from her husband. We argued the toss gently and she reluctantly went back to her own seat. In the meantime, in the manner of small boys, Aer John had been poking and prodding and had found that the seat was in fact, operable and so we went to our original seats and the Japanese lady could be accommodated where she chose to be. Had we been lied to/fobbed off? No. We weren't on G-VHOT. There was a last minute change of aircraft and we were on G-VFAB so it is entirely possible, especially from LHR where there is more scope for change, that the reasons with regard to a change may well have been correct at the time they were given.
To bring it back on to topic, seat changes are done for a variety of reasons which may have been correct at the time of change. Many years ago, before one could select seats on-line - or indeed book on-line, I had selected seats via my travel agent. It was in the days that long-standing V-Flyers may remember when, in the days before security tightened up, a staffer gave us the details of which specific aircraft were scheduled to fly each route ex-LHR up to two weeks in advance. We were to be on G-VHOT to SFO and were seated in what is now 20 and 21K. (The config was different because the upper deck was UC/PE before it went to all UC and then to UC/Econ) On check-in we found that our seats were changed and we were now in 21 and 22K. We were told it was because the seat was inoperable. On board I found a Japanese lady sitting in my seat because she had realised that side-by-side was better than being across the aisle from her husband. We argued the toss gently and she reluctantly went back to her own seat. In the meantime, in the manner of small boys, Aer John had been poking and prodding and had found that the seat was in fact, operable and so we went to our original seats and the Japanese lady could be accommodated where she chose to be. Had we been lied to/fobbed off? No. We weren't on G-VHOT. There was a last minute change of aircraft and we were on G-VFAB so it is entirely possible, especially from LHR where there is more scope for change, that the reasons with regard to a change may well have been correct at the time they were given.