Originally Posted by
chris1979
I don't wish to doubt KARFA's knowledge of the rules (he knows them!) but I've not had any issues guesting someone travelling with me on the same IB flight ex T5 into the CCR. so I am pretty sure the (unwritten?) rule ex T5 is that it can be used for any flights departing T5 with guests (we had BA BPs but IB flight numbers).
Remember Iberia in LHR T5 is coded so the BA flight number is the prime code for the flight (so to BA's systems it looks like a BA flight operated by Iberia, so the IB code is the codeshare).
So BA treat everything from T5 as a BA flight. In JFK an IB flight is treated as and IB flight.