Originally Posted by
orbitmic
As for others' experiences, as jerry a. laksa rightly says, we have heard both lucky and unlucky reports over the years, so some people will continue being lucky and others unlucky (and any change of seat or configuration will pretty much guarantee the unlucky outcome) but the rule itself is pretty straightforward and therefore the existence of some lucky escapes does not create the sort of precedent that one could use to request the same.
What seems to happen is that BA run a routine which validates eligibility for seat selection. In the case of F cabins, this is run very regularly and if you have 1A or 1K selected and have dropped from gold, it is highly likely that you will be booted out of these seats.
In other cabins, any equipment change (even if changed back straight away) will similarly prompt this routine to be run. Otherwise, it is luck of the draw whether the routine is run against a particular flight or not.