Three weeks ago I flew EWR to LHR and was NOT given access to the fasttrack. I was in a paid Business seat.
It took 50 minutes to clear UK immigration. It was the worst experience I have ever had at LHR. I used to fly UA in Business and got fasttrack from them no matter if paid or upgraded (from Y).

This is HUGE negative for CO at LHR. I almost went back last week to LHR and was going to book through IAD on UA to not go through that again. (Again would be in paid Business.)