border - legal - has to be minimum of 10mm away from any digit
phrase etc at bottom of plate - perfectly legal, distance away from digits as above
3d text - no longer legal according to merseyside police officer who checks our number plate log book @ work
images at side of plate - not 100% certain on this, there was a law came in saying you could only have euro logo or nothin, then that changed to country flags, but i think its been further relaxed so that anythin is now allowed but im not certain, i know we only make a few @ work, like st georges cross, union jack, welsh dragon etc