Some very interesting post plus the usual rubbish
Re fire fighting
LHR response team made absolutely the right call in closing the airport, this a wide body jet and the fire service would have had little or no idea what they were dealing with when someone hit the crash bell, was it empty or full of pax & fuel, if this fire had taken hold, well one only has to look at other similar ground fires!!!
If the aircraft was being prepared for service, then its likely that battery masters were on and ground service buss powered, so power to the galley's would be available, perhaps the ground crew decide to make a brew or warm their bacon buttie's up? so oven fire, IFE short circuit? guess the HF stuff is up in the roof area, an IFE short should trip the power off an oven fire might not or someone (cleaner?) having a crafty fag......
Hopefully we will know before the markets open on Monday