Originally Posted by
TravellingSalesman
I would say that BA should refund the full amount, and often are far too reluctant to do this when they downgrade.
Although in this instance, BA didn't do any downgrading. It was ultimately the passenger who insisted on being both downgraded and re-routed (onto a different airline), because that was what was needed to get where they needed to go. And it wasn't even triggered by anything that BA did; it was the operating airline's cancellation.