I am sorry to disappoint you but you have seen nothing of the sort, you just think you have. The 767 is a BA owned aircraft, there is likely a little plaque somewhere round the flight deck saying the aircraft is leased to BA by XYZ bank of Japan and the aircraft appears in the BA 767 manuals. At no point has the aircraft been sold to BACX, nor do the LHR 767s which occasionally replace WH when it's tech belong to BACX.