Your number plates. Friend and I got stopped because hers were dirty and not readable. You can be fined for this but she had a nice chap who just have her a warning and she found something to clean it with. Me, well after I came up 'no trace' (because they like to check passengers) I embarrassed myself by saying quite loudly ' mines fit take your time with your details' I too had a nice chap and went a little scarlet. Aren't they young!!!