I recently had a query about guest access to the Heathrow T3 arrivals lounge. We flew in Business and we are here now and have a definitive answer. EXP (OWE) is allowed access, even if in economy, but no guest or companion may enter. I know I took my wife in with me once before. They told me that "years ago" you could bring a guest but no longer. And you cannot pay to enter either.