Not sure if anyone will pick this up, but thought I would update, for those that were kind enough to offer advice and help.
DD agreed to do her video interview for the police. In this interview it finally came out, that as they were having sex (which she hasn't agreed to) she asked him to stop as it hurt. He said, it'll be because it's your first time, and just continued.
Further, it came to light that he had pestered her for nude pictures, which she sent. Foolishly, I know. Seems no matter how much you tell your teenagers not to do these things, it falls on deaf ears. Peer pressure is stronger, I guess.
We also received threats from this boys fringes, that put our lives in danger. He also spread very untrue rumours about DD, which led to her receiving a lot of abuse from her peers.
So, the police have been great. They arrested him, and seized his phone. He's been interviewed twice under caution. His friend that sent the worst threat has also been arrested and released on bail.
I also learned that there had been an issue with a previous girlfriend. I've spoken to her parents, who don't want to pursue matters. However, they did (at the time) contact his parents and threaten the police if he didn't stay away from their daughter. This in particular makes me so angry. His parents knew, but they let him into our lives and helped him with lifts etc. They let DD into their home and left them unsupervised. And they knew.
Sorry it's a bit of a ramble. Probably not in order! It's been an awful time. DD has only just gone back to school.
Given the latest statistics released on rape charges I doubt he'll be charged. But I will know that I have done my very best for DD.