It's not only lane 2 blockers on two lanes. On a 3 lane with HGV's in two lanes, the speed in lane three is reduced to that of the slowest car, and the slowest car is often the slowest to pull in after overtaking. This is often well below the limit.
DaveW '05 Red Roadster S1 '16 Yellow (Not the only) Narrow AR GDI Plus 4
