Originally Posted by
Smirnoff
It's not that they are poorly clued up at all.
What you are seeing is the LHR staff correctly following policy, which is NOT to through-check bags to onward connections on non-OW operated flights, unless it is all on one ticket.
Sorry to contradict an "evangelist" but that's simply not true. There is no official policy on this, just a guideline to try avoid interlining baggage on separate PNRs. I understand why, there's presumably a question of partial liability.
Fyi, last time I used the LHR T5 F check-in and had asked for my baggage to be interlined to another carrier, this time RJ another OW airlines, this was refused on the basis that the next flight segments were on a different PNR. So I think some check-in agents at BA's home hub are simply making up the rules as they go along or interpreting the 'guidance' as scripture.