Originally Posted by Globaliser

Is that really what would happen? The bags would be loaded onto the onward flight even though the passenger doesn't even have a reservation for the flight?

I thought that the stories of bags going missing at the interline connection point tended to point the other way: the second airline (BA, in this case) won't load the bags until it has linked the bags to a passenger on the flight. And even if the passenger has a reservation on the second flight and boards it, that doesn't mean that the bags will necessarily get loaded. as the bags themselves may still not have been connected to the reservation by the second airline. That's why the passenger should show the second airline their bag tag receipts when checking-in or boarding the second flight, so that the link can be made and the second airline can load the bags.

So many stories of people whose bags go missing at the connection point seem to involve the bag tag receipts not being shown to the second airline.