(09 Jul 2014, 9:11 pm)VolvoMarkII wrote Its not an 'alleged law'. Stop being arrogant about it. You asked the question and you got an answer. Look up the The Road Vehicles Lighting Regulations 1989.
This may allow use of white lit destination screens at the rear, but it does quite specifically state that light for purposes of illuminating a route indicator (in the case of London rollerblinds). It makes no mention of the white light being the actual route indicator.
Its open to interpretation and as already suggested, it may only take one very particular vehicle examiner to decide said vehicle is not conforming to regulations.
If it was Arriva doing it, not Go North East, he'd be well against the idea.