Is the reference to OWEs written anywhere that BA check-in staff can refer to, like the lounge access crib sheet? I've had issues checking in a bag early when travelling ET as an OWE from LHR.
Can't find anything "officialese" - I guess there may be local outstations where early bag acceptance may be a problem (because there may be no BA baggage staff ob duty for example).
We were all advised in the "Daily Brief" a while ago that early bags can only be accepted for Premier passengers or Prems, Golds, Silves, Emeralds, Sapphires travelling economy (but just for a few bags - not with loads of family or friends' bags too or the system will get swamped!)