But so often is the case that you are doing 100 in the outside lane (where the limit is 100) and you have cars, vans etc right up your a*se - you are driving right on the speed limit but feel under huge pressure to move over straight away.
I always move back into the other lane as soon as its safe as its not worth crashing over but I find these types of drivers don't give you much time!
Agreed, there is no excuse for aggressive tailgating like that. A simple flash of the lights should be enough the encourage people to move lanes if there is a need to do so. Never try and slow down a speeder by staying in lane, get out of the way and let them on. You can wave as you pass them after being pulled in further down the road.