My wife is a senior researcher for the MOD specialising in Sexual and violent assault in the military and she has explained that to me before but we have a friend that works for CARA so I sent her a whatsapp to check, especially for you.
It's not an Essex only law. It comes under Safe-guarding requirements and is something I was trained with when I got my enhanced DBS clearance for a voluntary role I have. So maybe not common knowledge amongst you or your peers, so sorry for that.
You seem very angry and upset I hope you're ok mate, I never wanted to insinuate you were stupid, just that you're asking for proof of something that is actually true and in that instance the burden of proof fallacy won't fly as a decent argument in my sub.
By position of authority, it would be someone like a police officer or teacher, care workers, anyone who has the potential to abuse people further would be subject to this kind of report and statistically not much is likely to come from it. As you stated earlier, without the victims statement there isn't much to go on, but an investigation can certainly be triggered this way which is the point I came to make for you.
If you'd like specific evidence about CARA you can call them on 01206 769795 and they'd be happy to run you through the logistics if you state it's for research purposes.
Also; Here's an excerpt from the Met-Police Website:
If someone you know has been raped or sexually assaulted, and doesn’t feel able to speak to the police yet, please report it yourself using any of the methods above. We’ll record the incident and help you to support the victim if needed "