Years ago on a non stop B747-236 from London to Narita (Tokyo) an augmented crew, Captain and two First Officers, gave time in the crew rest bunks behind the flight deck for each pilot in turn to rest during the 10hr 30 min sector. Sadly, the Captain died while asleep in his bunk, over half way enroute. The two experienced First Officers called for medical help, provided by a passenger who was a medical doctor, and confirmed the death. The decision to continue was made as the alternate was to divert to a remote airfield in the the Soviet Union with 300+ unwilling passengers and crew. The flight continued to Tokyo where a safe arrival was made.