This guy www.framptonsplates.com/ retired and sold the business. The address in this website will re-direct you. Should be ok if they keep the same standard. The rear numbers/letters are fixed to an aluminium back-plate. If yours is ok and not too many holes I imagine you can get the black renewed and the plate posted to them. Bear in mind it is illegal for anyone to supply a number plate without bearing the manufacturer's address and they will need docs to prove the number.
Thank you for your help and advice, I have now ordered some plates from Jessops formally Framptons they are in Sheffield. BEWARE though as I'm currently out of pocket at the moment to the tune of £68 as I ordered some plates from PEAK PLATES not ACE PEAK PLATES just to make that clear and I will not be getting my money back anytime soon as the man at PEAK PLATES has gone to ground despite my attempts to contact him. So if you are ordering plates for your own car please make sure that you don't fall into the same trap as me.