To the best of my knowledge (as I don'y actually work at LHR), in the hangar, 3 on 3 off 12 hr days, segmented C checks on 744 and A340. Work is carried out in BMI hangar. Smallish team supplemented by BMI guys. there is an advert for an Engineer position in the hangar at the moment, not sure if I can put the url up but here it is anyway
job there was also recently an ad for a Line Engineer as well, not sure if they are still after someone as it may of been filled.