Just to clarify, for a cancelled BA flight you can rebook for BA flights on the same route up to any date within ticket validity as long as there is space in the same cabin, you do not need same selling class availability. This also applies for reward bookings, so you do not need reward availability for the new flight, any selling class availability in the same cabin will do.

There have been a few variants of this since July when it was introduced, and this is the latest one:



This does not apply to non-BA flights though.