The law is quite simple relating to front reg plates on cars, you must have one. If one is not displayed then offence, now £100 not £60 but the good news is no points.
The reg plates on you car must be up to British Standards so must carry the BS number and the postcode of where they were made. If either of these are not on the plate then they are not reg plates so £100 fine (no points).
If any alterations are made to the plate, i.e.screws placed as to change the look of the letters or spacing being different from the normal, offence and £100 fine.
The police have the power to seize the reg plates off your vehicle as evidence so leaving you at the side of the road without plates meaning you can't drive the car as it has no reg plates!!
A little known point is that if you buy a private plate from the DVLA, you only buy the rights to use the plate and they can take it off you at any time. If the Police tell the DVLA they have issued a fixed penalty notice to you and you pay the fine or lose a court hearing the DVLA can and do take the plate off you, normally after three tickets.
Good news now is that most Police don't bother with this sort of ticket, it's normally just Traffic Police and you'll most likely only get one if you we're driving like an idiot. If you set off a speed camera and they manage to track you down, you may end up in court and they won't appreciate the lack of a reg plate, so expect a bigger fine.
Myself I can't see the point of not having one on the front of the car as it just seems too much of a risk for little better look.