Keg, you say the wind never dropped below 17kts on the RWY but ATC said the tailwind was 15kts? The BA crew said it was 22kts approaching the flare, it may have been less on the ground? I know at our airline we are allowed to take the ATC wind as the definitive source for judging tailwind components. So all in all a BA Aircraft said their limit was 15 kts, ATC confirmed the tailwind was 15kts and they landed.