I wish people would be a bit more careful about what they write. The discussion on cancelled awards have happened many times including at a time when BA reps used to visit our pastures and bothered to answer.

They were very explicit that award buckets are just part of the standard inventory so when you cancel an award, the RM system will pick that bookings have gone down on the flight and this may release inventory in award space and/or cheaper paid buckets than previously available immediately or the next day (and this is likely perhaps at a time the flight is widely open in all buckets), but equally it may not. In fact, there have also been many people mentioning cancelling awards that did not result in award seats becoming available to book on the flight.

Claiming that when you cancel award tickets, this will result in them going straight back to inventory so that award space automatically becomes available is plainly wrong and can mislead others. That is simply not how it works and space becoming available this cannot and should not be taken as guaranteed.