Originally Posted by
matinicus rock
Thank you colmc - one more question - what if the connecting flight was on American, but still on a different PNR?
In that instance they will. From ba.com:
•Baggage will normally be checked to your final destination, provided your journey is on the same ticket. However, if you hold separate tickets for the flights in your journey, British Airways will only through check your baggage to your final destination if the connecting flights are operated by British Airways or by another oneworld airline.