Yes ... hold onto your BA CW Boarding Passes and all will be fine. Have had similar turn arounds at HKG and never any issues. Departing the plane usually fairly swift and train down to immigration should offer no hold ups. Once though immigration Bag Collection is pretty quick so then exit up up the stairs to check back in for Cathay. Lounge Princesses will welcome you with open arms with your BA Boarding passes. See if your gate is displayed and if at far end make your way to Pier lounge for a great experience.