Clavinova... I meant it was fairly pointless to speculate on whether the previous teacher was marking generously or not. No one could judge this unless they had access to the previous and current teacher's marking, of similar assignments. So the only people able to actually comment on that are the HoD or similar within the school. That's all I meant. You seem to have expanded this to apply to the rest of my post.
As regards the rest of my previous post, I am an experienced teacher/subject leader of GCSE subjects in state secondary schools, so therefore I am not speculating about what is likely/typically/possibly - I am talking about my own experience of these matters.
I'm curious as to how you know so much about controlled assessments and internal appeals procedures? Are you a teacher or an exams officer? Do you work in a school in an admin role?
I must be honest that I was not aware that schools should have a formal internal appeals procedure for controlled assessments - this is something that the school's Exams Officer would deal with, and probably wouldn't be something general staff would be aware of until/if they had a query from a parent that became a formal appeal. I have never had a formal complaint from a parent about controlled assessment work, it is quite unusual in my experience. Although, I would have communicated in much more detail with a parent than seems to have happened here.
Controlled Assessment grades are only final after they have been sent off to the exam board (usually by May 15th of the relevant Year 11 academic year), the mark may then be adjusted by the exam board if the school's marking is found to be inconsistent/too high/too low. Up until the school sends the marks off to the exam board, the marks are in the control of the school and could be adjusted as a result of internal moderation or a re-mark of a specific CA piece if it was felt an error had been made. Exactly when schools do their internal moderation is entirely up to them.
I would repeat my advice that if the OP is keen to pursue this, that a detailed email to the HoD/HoY/Head asking specific questions is the way to go. The OP should ask about the internal appeals procedure as well, and ask for this to be applied.