Originally Posted by
SFOSpiff
That has not been my experience with BA. At Heathrow, perhaps, but not everywhere. I once arrived at SFO in J and was connecting to a Virgin America flight, which also uses the int'l terminal, so I had airside access to the BA lounge. The reaction was something very close to "What? You must be joking."
The difference is that your connection was not BA/OW, while the OP's is. That said, did they ultimately let you in?
My experience (albeit limited) has been BA being more accommodating than they technically had to be (letting me use F lounge on a next-day AM connection when departing in J).