Such numberplate surrounds are perfectly legal and don't let anyone else say otherwise. Nothing in legislation states you must have a plate surround not you shouldn't. Clearly though it must not block and views of the plate. I've got one on my golf and I also have LEGAL pressed plates. I have a whole document relating to legality of pressed plates in the correct circumstances if anyone wants it (off topic I know sorry). I can back all this up with fact and through my own work/experience.
MC71 - i'm gunna stick my private plate on which is 5 digits. I'm gunna stick a smoth front grill on and relocate the plate somewhere but can't find a place it isn't blocking an air intake!! Out of interest where's yours? (Sorry, off topic again I know :()