When doing GCSE exams, do you HAVE to wear school uniform or is it at the schools discretion?
If your school has declared it a non-uniform day, it should not be a problem to sit the exam once you have proper ID. The examiners are probably informed of this beforehand anyway so that they would expect some people to show up in regular clothing. Additionally, if students writing GCSE exams were required to wear the uniform on the non-uniform day, then the school would have (or, should have) made it clear to you beforehand. Since they did no such thing, you should be fine wearing regular clothing. Personally, I would wear my uniform and have ID with me just to avoid any potential problems with external examiners, but I am just paranoid like that. However, I am quite sure that there would be a mix of both external invigilators and school staff present in and around the exam areas of the school. So your teachers would recognize you anyway if you came in plain clothes, so it should not be a problem. GOOD LUCK with your exams my friend, God bless!