Re: Surely he is innocent or guilty (of something)?
"We seem to have a new grey area where you have nothing "proven against you" yet you are allegedly a threat to society and can have your rights taken away from you?"
The police already keep information on innocent people in their databases. They say that helps them to find possible suspects when a crime is committed. Given that such "soft intelligence" is probably often no more than hearsay, unfounded malicious allegations, or just degrees of separation from someone being investigated - then probably most of the country's population has an entry.
The police often seem to arrest people these days on some vague "suspicion" hoping that the enabled search will turn up some evidence. So called "fishing expeditions" re often part of an ever-widening wild goose chase. The innocent person then has their DNA etc retained. Local newspaper online files might report the arrest without the fact that no charge was subsequently made. A perpetual official black mark against the person's character for possibly no reason at all.
The Snooper's Charter will amplify that store of information to include inferences on everyone's political, sexual, and social interests.