it's those people who sit in the middle doing pretty much the same speed as traffic in that left lane.... just speed up a bit and pull in front or slow down and pull back in!!! is it really that hard to do?!?!?!apparently...yes.....yes it is xD
same applies to the slow overtakers, they overtake (usually cutting out infront of faster moving traffic causing a string then almost cut the car up in the middle lane and then usually slow down.... which just means the dude he/she overtook is just going to jostle for position again if they don;t want to travel at their speed.
damn I don't half go on sometimes xD
I think both of those scenarios are down to people wanting to stick close to the speed limit. Essentially they are doing 70-75mph and overtaking cars going slightly slower. They don't want to floor it up to 90 in an overtaking maneuver because they consider it to be wrong, even if it would clear the outer lanes quicker.
As the middle lane hoggers issue in general, one of the causes as I see it is because people wanting to drive at the speed limit get frustrated having to keep ducking in and out of the inside lane where invariably they will come across slower traffic. In some cases they then can't get back out again because there is a stream of middle-lane traffic passing them who don't pull out into the outside lane to let them across (and if they do, they get flashed by the people wanting to do 90+ in the outside lane).
Gonna be interesting to see how long it is before someone claims they were 'unjustly' busted for middle-lane hogging e.g. coming up to a junction and wanting to give room for merging traffic.