One other option that I like is to do the back-to-back the night before, without an overnight in e.g., Oslo.
So if you were flying to Australia on Friday, you'd fly to Oslo on the second-to-last flight of Thursday, leaving Heathrow at 5.35, departing Oslo at 9.30 p.m. and getting in at 10.40 p.m. You then do whatever you'd normally do on Friday, giving you a free choice of LHR-HKG and LHR-SIN departures to route on to Australia on Friday, as none will take off more than 24h from the OSL-LHR landing in London. As such, you're not liable for APD or charged for a stopover but you can just show up with normal luggage for your outbound long-haul leg.
Last edited by Cymro; Sep 10, 2019 at 5:28 am