Let me preface this with the following:
1. I am not a pilot.
2. I am not an engineer.
3. I am not an expert.
4. I happen to work with solvents and other Kerosene related products.
None of the above matters really, just don't want to set myself up for a fall.
I DO NOT believe these fuel theories, for one reason and one reason alone... I cannot believe that in the 10 (or 12) years that the 777 has been in the air that this is the first occasion that this has happened.
Look, flying from Beijing to London may be a cold route, but can somebody tell me if it is the coldest? Surely the Boeing engineers over-engineered the fuel system to take account and over-compensate for these situations?
I think fuel is an easy speculation (one which was being bandied about by people who have since ended up in the WAGs thread), c'mon people, tax those expert brains of yours!
Lacking the necessary expertise in this area, I more inclined to think it was an electromechanical failure of some sort.