No, but it isn't the first time that this has been reported to be allowed and I'll bet it won't be the last time. When there are genuinely exceptional circumstances - and the widespread disruption this weekend probably counts - then BA has been known to show flexibility of this kind. We should not expect it if we oversleep on a fine summer's day or if our cab gets stuck in a traffic jam on the M4 - or for that matter we should not expect it, ever, even though it does sometimes happen.