About three years ago, BA ground staff at Heathrow gave me a time-wasting runaround. I asked to see the BA Airport Manager, and politely explained the problem. He apologized, then checked if an upgrade was available for the flight to Australia from J to F. No seats were available, so the verbal apology would have to suffice, and I heard nothing more.
But since then I seem to have an almost automatic upgrade with BA, on routes as remote as BOM-LHR (twice into F), MEL-BKK (from discount economy to premium economy for all the family), SAO-EZE (into F), and so on. Unless it's my good looks
I seem to have got onto their computer system as an autoupgrade. Several more long haul flights with BA coming up next month, so see what happens........
Moral of the story - If the reason is because of a computer entry, it shows it's worth talking to the airport manager (who has the authority to do such things as upgrades)