Agreed, i don't think the PM wants to get everyones attention.
The time I saw him in his S class, all he had was one normal car
driving behind him between the two lanes, acting as a body guard
and preventing any cars from overtaking him or driving next to his
car. Only way i knew it was the PM car was because the taxi driver
recognised the number plate and told me. I'm not quite sure if the
PM has massive convoy behind him like you described, maybe some
other highly distinguished person?