There is of course a great ton of evidence. For starters there is the way in which the police response to the miners strike was organised, where aspects of the state not usually employed in industrial disputes were deployed against the miners (eg the benefits system) and where a manual of permitted tactics was used, a manual which has never received any democratic sanction via parliament. These means form the basis of national police organisation to this day. E2A and the normal freedom of movement across the country was abridged.
There is the use of surveillance, cctv, anpr, facial recognition. More than a decade ago surveillance scholars wondered if we'd sleep walked into a surveillance society. We're likely the second most surveilled society in the world, after China. And there is fuck all bar cops' consciences controlling the use made of information gathered by electronic surveillance. There's scanty statute law on the subject.
but a police state is not just unaccountable cops monitoring who they like, it's also people's everyday experiences. More than 30 years ago the Hackney community defence association said black communities already lived in a police state. What's happened since then is that it has enveloped the rest of us too. You almost never see cops actually doing anything about crime. Not burglary, not mugging, not the great shoplifting wave across the country - not vawg. What are the cops doing? What is the purpose of the cops if it not the prevention and detection of crime? For me what's happened is the rise of colonial policing in the metropole. The sort of policing formerly used in Hong Kong and Ireland but not here. The aim has shifted from the control of crime to the control of the population. This is why eg the vigil for Sarah Everard was attacked. Any connection between police activity and the solution of crime is purely coincidental. The expansion of police power and their pervasive influence across society - not simply in those sections which might be thought relevant - are what leads to my conclusion we live in a police state and against which your utterly pitiful objections of inefficiency and limited freedom of speech weigh as nothing.