Growing up as a very middle-middle-class child (you knew that, didn't you?), respect and benefit-of-the-doubt for the Police came up with the rations. It wasn't until I mixed with the soldiery in my first regiment that I had regular dealings with people for whom "All coppers are bastards" was axiomatic.
These things don't change overnight but it seems now that we've gone past the point where the middle classes would give automatic credence to the police. The symptoms are many and various. For me, the last straw has been how they allowed themselves to be captured by woke doctrine, typified by their being in thrall to Stonewall's outrageous protection-racket proselytizing on the trans issue, to the point where fairly moderate Guardianista feminists fear for their freedom of speech at the hands of the police. Others would point to the way the police seem often to lie and prevaricate as a first reflex on sticky issues. Or the way that a Safety Case must be defined before anyone can get stuck in. (In my street last week, 5 (five) police attended to round up a perfectly peaceable, indeed rather bewildered, lost dog.) Or the way recruiting standards have been remorselessly lowered, firstly to accommodate "diversity" targets and nowadays just to recruit anyone at all. And that's before we get onto the outright criminal behaviour of some individual officers.
This is a very bad state of affairs indeed. We know from places like Mexico and a hundred other hell-holes that when the police feel themselves totally beleaguered and unloved, they retreat into their corporate shell and become just the biggest and best-armed gang on the streets. (Well, in some countries, not even the best-armed.) Large-scale corruption and worse follow swiftly.
Reputations can be turned around: but it ain't easy - particularly when the zeitgeist runs strongly against tough, dictatorial leadership of the sort that can (sometimes) turn around, e.g., a foundering corporation or a military unit; though it seems the new Chief Constable of Manchester is giving it a go. But the likes of Cressida Dick? Don't make us laugh.
(An example of deep and successful reputational turnaround one might have noticed over the years is Private Eye: under Ingrams it became a byword for casually inaccurate stories and consequent lawsuits, and the courts pretty much gave plaintiffs the benefit of the doubt. Bit by bit, Hislop turned this around, to the point where today the courts actually give the benefit of the doubt completely the other way around. Ask any PR firm how they'd advise a client who was contemplating suing the Eye just now.)
But these things aren't quick to achieve, and are in any case many times easier for a small organisation. It's gotta be done, though. And in terms of the biggest force, the most pivotal force of the lot: does anyone imagine Sadiq Khan is the man to reform the Met he's notionally responsible for?