As far as I can tell, it's 12 GCSE's including an A in Latin.I did check. 12 GCSE’s and an A’level in Latin always seem to get mentioned.
Although his media fanboys airbrush out the bit that he went to a famous independent school.
Obviously most people who don't go to famous independent schools don't get the option to do GCSE Latin even if they'd be interested. I know for a fact Tideway didn't offer that.
I checked on Wikipedia, it cites this website which doesn't look any more trustworthy to be honest. As far as I can tell, he doesn't have any A-levels (which require, you know, some sort of actual effort) at all. I'm happy to be corrected on that if anybody can find actual evidence.