surely if you pulled in as soon as safe to do so then they wouldnt have time to undertake, 
Lorries on the inside lane, always just get passed them as well just incase they suddenly swing out and someone else ends up in the middle lane.
Was literally 3 seconds after going past, just saw the car in my rear view (thats when they teach you is safe to pull in) and then just as I indicate the Audi is there. 
I was NOT hanging about either.
I am with Chuff on this one.. I have got to the point now where I look at the traffic ahead and you can slate me for it but if the inside lane is clear and there are people queued up on the middle/outside lane I carry on going down the inside lane..
I am sick to death of people who sit in the middle lane, motorway is the simplest of things, yet so many people are too stupid/arrogant/selfish to bother driving properly. I used to come down the mway at 11 at night, see a car on its own in the middle lane, come from the inside lane all the way out, giving them a flash and coming all the way back in to the inside lane in front of them, but they don't move.. so now i don't bother.. I just carry on cruising down the inside..
My biggest bug bare with motorway driving, is say i am doing 70 in the inside lane, approaching a vehicle in front, i look in my mirrors and someone is doing 72 alongside me.. and they force you to brake to to lorries speed i.e 56. If i am in the middle lane, i make a point of trying to judge others speed so if they want to overtake i can give them a little flash and move to the outside..
As well as this the other thing that really pisses me off is when coming up to traffic crawling along, i try to leave a decent gap, cruise up to it, leave a safe braking area and then 3-4 cars dive in the gap and cause you to slam on.. yet they go nowhere.. just sit in the traffic in front..
And don't get me started on tailgaters, ok I get it, you want to get somewhere, so do i.. I would be happy to move over and leave you go, but THERES NOWHERE TO GO. WE ARE IN TRAFFIC.. FCUK OFF MY BUMPER!!!
Rant Over.