Compared to Miami, LHR is a breeze.................
Flew CDG-MIA on 26th, immigration hall full in MIA but all desks manned, was through in approx 15 minutes, no problem.
Did not arrive at LHR on this trip but did depart from T5 to CDG, arrived into MAN from JFK and no problem at all at immigration, straight through, only had hand luggage and was in the hotel less than 30 minutes after landing.