Funeral processions in America...
...are way too long. You have to sit there at the lights while every man and his dog passes with their flashers going.
Not so in England. Yes, you should give way to the hearse and one, or perhaps two, immediate family vehicles but you have gone way over the top here.
In England, funeral processions don't enjoy any privileges under the traffic regulations. They're expected to obey all the usual traffic rules. In addition, funeral processions have no special rights of way on roundabouts or at traffic lights. There are no concessions to following vehicles that risk losing contact with the hearse or the car in front and not finding their way to the cemetery or crematorium.
The exception to the rule is when a cortege comes under police control. This happens if it's a very long procession or if it's moving slowly behind a horsedrawn hearse. In these cases the police have the authority to hold up traffic at lights, junctions or roundabouts.
I think you need to regulate. From Washington.