Hi everyone - thanks again for all the advice and comments. I'm sorry if I'm confusing everyone - the exact title of the exam is a BTEC First in Art & Design, and from the school handbook "The portfolio of work produced for each unit is marked internally and moderated by an external moderator".
So, as I said before, she may well have done something wrong although she claims she wasn't told she wasn't allowed to bring the work home on this particular occasion. She also says she has several witnesses (most of the class) who will testify to this. And also, this particular unit of work has another session devoted to it next Tuesday.
In all honesty, I don't really understand what the teacher has done here as it seems that the unit isnt even finished yet. I understand exactly what the teacher has done/said to DD, as DD is clear in her recital of the incident. I intend to bring my confusion to the meeting with the HT on Monday and hopefully she can shed some light on it, and tell me how this one teacher can threaten the thing she has. And can I be clear here - if DD has done wrong (still would be very surprised if she has actually "cheated" though) then she should, of course, be penalised in some way (not sure disqualifying her from all GCSE's is the way to go though). What I strongly object to is the way this has been handled, and the name-calling/tale-telling/lack of information which has happened.
DD has written quite a detailed version of what went on, and as someone mentioned above (sorry, can't remember who), we are taking her with us to the meeting, initially to wait outside. The reason we didn't say anything to school on Monday was because we thought there must have been a misunderstanding as no-one from school had contacted us, and they surely would have done so in such a serious case. And as I said yesterday, this still remains the case. I have tried ringing school today, but there are no staff in - I also went up there to deliver a letter to the HT setting out our side of things so she has a chance to do some investigation. Fully intend to be calm - will have DH with me too as I tend to veer off topic. 