All the car buying guides seem to concentrate on checking the car for faults, which is relatively straight forward if you follow the guidlines.
HOWEVER what is the legal process of actually taking ownership of a car. lets assume I go tomorrow view a car and decide to buy it straight away, what documents do i need to fill in etc. so the car will be mine.
i.e. in other words what is stopping the person who I'm buying the car from in saying I didn't pay them or saying I stole the car?