Of course in reality a hybrid of the above will probably happen!
i flew on Thursday and the sectors took me just over 1500TPs and back up to Gold....however, the flights have both posted and immediately zeroed out all my TPs, which have reset to zero and my account is still showing as Silver
i assume it it might shake itself out but you would think it is not very complex software scripting and given the BA systems know I took the flights then Gold should be automatically triggered