yes I knew that they mean't the V5 registration document but I still feel that it is none of their businness. Years ago car owners were told not to share details of that document with anyone.
I decided to tell them to stuff the badge as they are often a huge joke. Example the badge scheme doesn't apply in Westminster, Kensington and Chelsea and parts of Camden by order of The Secretary of State. You might get a preferential space at a crummy supermaket. I hate supermarkets and never go to them - my husband does the grocery shopping. So I can manage without the wretched badge