I shall type this very slowly for the benefit of Nooby who might be slow to read it.
He targeted her from the age of 13.
He sent her cards, cuddled her (as he did with other 13yo pupils) he made her feel special when she was going through a rough angsty patch at home.
She looked up to him, her teacher who played with a rock band - how very cool! He wrote a song for her, how romantic!
She was groomed for 2 years, from 13 to 15 years old. A child who had none of the life experiences we have had, a child who had never had a serious relationship with a boy before, a child who was going through adolescence, a child who trusted an adult, a child who has no hindsight or cynicism, a child who had never left home before.
She is A CHILD and he is HER TEACHER. Yet you still say that it's up to her if she wants to runaway with this man, who already has previous because presumably she's capable of making those life-changing and very grown-up decisions?
You don't think she was persuaded at all? You think that past experience helped her to make a rational decision?
What did he have to lose? He knew that he was being investigated and his other offences would come to light, so what does he do? He takes the 15 year old and he runs off to France with her. Thus avoiding prosecution (he thinks) avoiding his other indiscretions coming to light and where he is able to enter into sexual relations with this child quite freely.