The truth is that it is nearly always the fault of both parties. The Highway Code tells us to leave a larger gap ahead of us in front of us if someone is driving close behind, to allow us to brake slower and not get rear ended. We are then also told to obey the 2 second rule which, despite what ‘strider hort’ says is easy as you just slow a bit to create the gap then match their speed. If both drivers obey then there should be enough of a gap behind to stop if someone emergency brakes or enough gap ahead to brake slowly to avoid being rear ended.
In certain situations we should use our mirrors to tell us if it’s safe to brake heavily such as if we see a turning late, safest just to miss it, turn around ASAP and come back if someone is up our ass. In that case the car ahead would be at fault. in cases of distracted drivers rear ending people when not concentrating or looking ahead it would be rear drivers fault.
TheDE