BMI A330s use 55 and 44
AA 757/767s use 54 and 53, occasionally 48
BA 767 use 49
GT 320s use the spaces left, along with WW 737s
If rumours are to be believed, AA are to start some new services soon, possibly Dallas and/or Los Angeles?? There could be space if BD move all long haul ops to LHR if the Bermuda agrement gets tweaked.