Education (or lack of, inability to retain etc.) is the main problem. I've met people who were of the mindset that the driving lane is for the old and poor, and for those with **** cars that break down frequently. Don't ask me how people come to those sorts of conclusions when they've allegedly take a driving theory test that shouldn't leave anything to the imagination...

I suspect though, as do many, that bad motorway discipline stems from the fact there is no practical motorway driving component to the UK driving test. Change the driving test to incorporate motorway theory and practical elements, and the standard will improve. A bit of enforcement would help too, if everyone thought they'd get hit with a (say for example) £75 fine for camping in the middle lane without a bloody good reason they might pay a little more attention to their rear-view mirrors.