Aircraft surrounded by emergency vehicles at LHR?

[Dave's brother]

Last Friday night - 17 November at 2200gmt - I was an arriving passenger at LHR Terminal 1. Some distance away from the terminal was an aircraft surrounded by about five or 6 vehicles, all with flashing blue lights. It was hard to tell in the dim light what they were but they didn't appear to be fire crew, though a few minutes later I saw one fire engine apparently making its way to that aircraft.
The aircraft tail was pointing straight to me so a/c type and airline were impossible to make out.
Anyone got any idea what it was?

[Airline Tycoon]

Malaysian B744 rejected take-off with an engine problem, so the Fire Service were called as a precaution just in case his brake overheated.