I only finished my GCSEs last year; I pretty much failed them because to me a pass is a C or above and I don't think I got C or higher for anything actually (If I did it would've been for English). I think the highest grades I got were E's and D's, even for computer science I did awful because they wanted to do VB.NET and obviously I was not going to spend a year doing something I had been learning about 4 years prior to my GCSEs... Then again, the people who got the top grades didn't have any skills outside of what they were taught by the teacher, so it is a negative for them and not a positive really. Grades don't prove how skillful you are or your true potential, they just put you under stress and cause more trouble than good in most cases IMO.
I didn't even attend my mocks, I bunked them.
And I didn't even bring a pen to the real exams I don't think... Then again I didn't care back then and I still don't care