Rhubarbz, I aplogise, that was how I read it yesterday and I did get upset. I am sorry you had a hard time as a teen, its not easy for anyone. I wouldn't go back to being that age if you paid me!
I see the whole ADHD thing kicked off an argument. I think it is a good point - if kids are misunderstood due to a special need then things are not going to get better. Asking the question does no harm and I am grateful to the posters who pointed it out.
Anyway, I managed to get hold of her teacher today and he basically said she was asked repeatedly to be quiet but when she rolled her eyes and huffed at him, she was sent from the room and rightly so. When she came home, myself and DH sat down with her and used the tactics so many of you suggested and didn't discuss it with her, just "this is what the teacher has said, we have no reason to believe he is lying to us, you are in the wrong and you will apologise and you will apologise to us for speaking to us so badly yesterday." She immediately got angry and started saying, "The teacher exaggerates, why don't you ask him about so and so who was mucking about," and we just repeated that we were not discussing it. She started crying! Stopped being angry, admitted she was in the wrong and apologised, so it worked! In the past, I have always let her talk because both myself and my husband were raised as very much, "you do what you are told whether you like it or not." and we always said we would talk to our kids. But what has been happening is that she starts winding herself up, it gets very convoluted, it becomes a he said, she said situation and we end up arguing over something that has NOTHING to do with what we were originally arguing about and every one (mostly me and her) gets very upset and angry. We felt so Draconian by not letting her talk, but hey, if it works!
The good news is that her teachers have no concerns about any PD. The teacher who disciplined her said she is a good student and normally a pleasure to have in the classroom. I told him about the anger at home, he said they never see that in school but that his own kids were the same way at that age. It is easy to get angry at Mum and Dad because they still have to love you.
Beerwench good luck! I do wonder if horsey kids are worse at this age because they have to be so confident to ride. We should do a study.
So thank you everyone for the good advice, I shall be more of a benign dicatator from now on if that is what works. Much happier with her today and I am really pleased that she has promised to apologise to her teacher at the next lesson. I think she will do it as she normally gets on with him very well but I will be checking!