Oh dear, that's not good, going at that speed on a fast lane is like meeting a wall in it. My guess is it'slikely that this lady is at her wits end every time she gets behind the wheel and cannot cope but is being passed by her doctor fit to drive. She possibly knows she shouldn't be anywhere near a motorway and avoids them - she may have accidentally joined one. It is likely a massive ordeal for her to drive and should she use urban roads often then she is an accident waiting to happen. I think it is accepted that when rural roads meet urban ones is where the problems occur as these kinds of drivers just have no ability to cope with the change in pace. Older people living in rural settings become very isolated if they cannot drive and this is why country doctors are slow to take them off the road. If they potter around the locality they are an inconvenience to other drivers but are you unlikely to cause a serious accident. All drivers need to bear in mind when driving that we can and will encounter drivers like this on the road and be prepared for how they act. Either that or a lot more of these people need to be taken off the road. Even if they are taken off IMHO a lot of people are driving like everyone else is totally aware of their surroundings and are going to act perfectly in any given situation - this also leads to accidents as not everyone is paying 100% attention and may be distracted. This is especially important when the difference in speed between two sets of cars is vastly different. I've been in a group of cars behind a slow driver and gotten to a straight when the car directly behind the slow one did nothing. I then look to pull out and glance in my mirror only to note that a car that was not in the "convoy" and doing 60 to our 30 has decided to overtake 5 or more cars all at the same time having just come up on them and the straight at the same time. This will all go swimmingly if everyone has looked in their mirror before attempting to overtake....but the driver is relying on other frustrated people to have noticed them and behave correctly for everything to work out.