How to get number plate for old bike?

You need your V5C log book. This proves the registration number. You also need to show your ID. Your driving licence or passport is good. Take these documents to a registered number plate supplier. Many garages can make them. A place like Halfords can do it too. They will check your papers and then make the new plate for you. It is quite a simple job, just make sure you have the right documents with you.