Going SFO-YVR then YVR - LHR - DUB. Flying paid business for the UA and AC segments, then EI in single class Y. All on same PNR.

THE LAST I flew this itinerary, the *G lounge attendants told me that I couldn't use the lounge since I was flying Aer Lingus metal, even though it had an AC flight number and I am * gold.

Is this right? Can AC and UA sell paid C tickets through LHR to DUB with zero lounge access? I checked at the EI lounge, and they let me in but said they weren't supposed to.

Anyone know?