The problem of course with queues for passport control (not customs as that is normally a straight walk through the Green Channel) is that it is totally policed by UK Border Force.
Manchester has exactly the same problem in all three terminals, for which the airport authority is constantly being "put down" on Twitter. Unfortunately the staffing level, and even the number of e-gates in use, is in UK Border Force's hands.
Don't get me started on Security queues - that's a totally different kettle of fish which contains some pretty sluggish specimen.