Maybe rules are only there to be broken !
Or maybe not:
"ATC can direct planes off the NPR at an altitude below 4,000ft if this is required for safe separation from other aircraft or for other safety issues such as weather avoidance. Therefore, if a plane is not following the NPR, it does not necessarily mean it is doing anything wrong. However, if you do have a query regarding a particular aircraft you may contact our Flight Evaluation Unit, who will able to assist."