Original post by BlueSam3Every single part of this post is wrong, and the poster doesn't know what he is talking about.
GCSE grades go A*, A, B, C, D, E, F, G, U, with A*-C being one level of qualification, D-G a lower level qualification, and U being a fail. There's also an X (for people who don't attend the exam), Q ("marks not available" - it means something's gone wrong somewhere, talk to your exams officer), and A^ ("A with distinction", above A*, only in AQA IGCSE Further Maths). (NB: this all changes for people taking their GCSEs in 2017 onwards: then, the grades will go 9,8,7,6,5,4,3,2,1,U, with U bein a fail, 1-4 the D-G qualification, and 5-9 the A*-C one).