Me, I fear.
Being followed by a Corsa on the way back from hols a week or two ago, along a very long stretch of dual carriageway. Whenever I was stuck behind something that was slowly overtaking a lorry, the Corsa glued itself to the bumper of Mrs 12th's car. When the way cleared, I'd put my foot down to get up to speed, get past and then pull into the nearside lane - as per highway code etc. Each time, a substantial gap opened up between us and the Corsa.
I started to notice that whenever I did this, and no matter how many hundreds of metres of clear road ahead there was, the Corsa never moved out of the overtaking lane. It just sat there, gradually being wound up and glacially catching up after having been dropped. Each time I moved over to overtake something, I seemed to end up behind another vehicle that was doing likewise, but always slowly. So each time I ended up with the Corsa stuck in my rear view mirror, and each time it then refused to get out of the overtaking lane no matter how clear the other lane was.
I'm sorry to say that after a while I made a bit of a game out of it - ensuring that as the gap got down to 50m+ or so (i.e. it was perfectly safe to pull out, given the glacial rate of gain), I was always at the point of having to pull out to overtake. This went on for about half an hour. Not noble, I know. I'd like to pretend I'm not proud...