SxMan | seanp7 -- many thanks for your replies below: all very interesting and much appreciated.

Having delved a little deeper with BA, it would seem that I have been the beneficiary of a discretionary additional year of BA Gold status (much like yourself, SxMan), so that would explain my initial confusion as I had expected to lapse to Silver at the beginning of October. (It was good to know, seanp7, that the app seems to trump the website as this appears to be exactly the case in my situation.)

Again, thanks all for the insight -- I really do appreciate it.

All the best.