Guy came to view my car tonight, he's happy with it and wants to buy the car. Few questions about putting my plate on retention. I still have the old plates which were on it before I put my plate on, I'm right in thinking the car will return to this old plate? I know Il have to visit my local dvla to get the tax and stuff changed but is it going to cost me double to get the plate changed back and my private plate put on retention? Thanks in advance.