in all my exams my teachers have told me to dress smartly and i have usually found that this means a shirt and school trousers. others, i know, wear kilts or dresses for exams and i even heard of a girl who hired a ball gown for an exam ( whether she did this for a joke or not im unsure). i have always wondered if it would make a difference to the mark how you dressed. it's true that you would want to make a good impression but if it is based on appearance then it seems to make the exam worth alot less (in my opinion). it says nothing in the guide books about dressing smartly so it seems to me unfair that marks could be lost on clothing.
i would be really interested to hear about what you normally wear for your exams and if you think it makes a difference