Originally Posted by ReelChief
.....she knew that BA-UK could make bookings for A seats that BA-MRU could not. Whether they were holding them back from being gobbled up by RTW trips originating in MRU is not clear.
There is a little know yield management tool, class availability by point-of-sale. The same booking class has more availability in higher fare POS. It is prevalent in Asia, less so in Europe, Africa or USA. EF shows availability for POS USA.
One way to get around it is to book in higher fare POS, UK in this case, then queue the PNR to lower fare POS for ticketing. The problem is to convince BA UK to book it for you knowning that it will be ticketed in MRU (it will be tough to convince them).

If you have access to KVS Availability Tool, you could sometimes see that by switch hosts to different POS.