Just to flag that I used to prefer Seat Spy but in the past couple of months or so, Seat Spy's search results have been wrong for me and not reflective of actual availability on BA if looking to book particular dates. I had a quick look on FT and don't seem to be the only one with this problem either. See eg the more recent posts here SeatSpy and BA not showing some availability So for the time being, I prefer RFF which in comparison has been accurate.