Well there are all sorts of ways at looking at that but the short answer is yes. As soon as you make schools compete with each other for pupils and then put ambitious managers in the mix, you have a recipe for corruption. I do not believe for one minute that private schools are not fiddling their coursework but maybe they are less obvious about. For example a school that gets many of its pupils up to A and Bs in their coursework (usually by repeating it again and again) and then they get D and Cs in the exam is bound to raise suspicion. My wife moderated English coursework for both state and private schools (national and abroad) and on the whole state schools tended to be more accurate in their marking than the private schools. Gove removed igcse from state schools because he wanted our exams to be more rigorous but he had no power to do that for private schools. The question becomes do you believe his intention.