I am working on a story related to malicious use of the internet by a small group of English citizens that are targeting two US citizens. The group's activities have caused problems for the government in the past. Public knowledge of their activities would further embarrass the government. Due to the possibility of embarrassment and the known members' positions in English society and the government, the incidents and their involvement was suppressed.
I looked at the National Crime Agency (NCA) and it didn't seem right. Based on what I found it seems they only investigate Cyber Crime. What the group is doing is more Cyber Bullying, but that does not appear to be a crime in England.
What government agency(ies) in England would investigate this type of activity if they receive a complaint from the FBI (or other US agency).