Re an earlier question re Qantas, Gulf Air and Cathay.
QF left because of BA, as Golf-India Bravo has already said.
When Cathay Pacific joined One World, their services miraculously disappeared too. For One World, read one airport and one carrier.......London Heathrow and London Airways. London, London, London and again, London.
Gulf Air operated to Abu Dhabi, which at the time didn't offer significant connections. They said that they'd return when they finally developed Bahrain as their major hub. This hasn't happened, and possibly GF seem to have missed the boat with Emirates, Qatar and now Etihad developing their networks.