Originally Posted by
Reality_Czech
Point of Sale inventory control.
I don't think so. Note that while there is Q and O availability, there is no fare filed for Q and O booking classes, the lowest booking class with a fare is N. I suppose that does achieve control of lower price inventory originating from LOS, but it's not the usual situation of a booking class where "fare is filed but inventory in the fare class is not available from that destination for a ticket bought in your country".
You will never be able to get a ticket starting in LOS to LHR booked in Q or O on BA no matter where you buy it from.