BA would have a problem operating freighters in the current market-place, primarily because BALPA would want BA to pay the standard BA 747-400 salary. This would make them uncompetitive. Lufthansa split off their cargo operation and pay less than the standard Lufthansa salary. Cargolux, the other big long-haul cargo player in Europe, pay considerably less than BA. (Although a lot more than Atlas, it would appear). Air France don't count, since they still drink from the taxpayers' bottomless pit.
I would be interested to know BALPA's view on the idea of BA having a separate cargo operation, paying competitive rates. Would they prefer an American low cost carrier using American crews to carry BA's freight, or would a BA cargo operation paying representative salaries be acceptable to them.