There was an arresting picture in the papers last week. It was of an eight-year-old boy perched on the chimney stack above his terraced house in Welling, southeast London, smiling as he read a book. The photograph was taken as an entry for a school competition to show books being read in unusual circumstances. Unfortunately for the boy’s father, Jonathan Blake, a bishop in the Open Episcopal Church, the incident was reported by a neighbour, and Blake’s local police force decided that encouraging a child onto a rooftop was an arrestable offence – one so serious that Blake was arrested, handcuffed and held in police custody for 24 hours, charged with child neglect.

Blake is not a lunatic. He is a mild-mannered, devoted parent. He was encouraging his children to be imaginative and adventurous in response to the school’s challenge. His boys, aged seven and eight, do rock climbing and adventure sports, and on the day they climbed onto the chimney, they were wearing a safety harness and were guided up the roof by him, using secure footholds. The boy in the picture looks happy and proud. The police response has shattered that.

Within an hour of the boys coming off the roof, two fire engines and two vanloads of police roared into the street. Then, says Blake, “all hell broke loose”. Two female police officers asked to see the children, who said they were thrilled by what they had just done. Thirty seconds later, half a dozen male officers burst into the house and – without discussion or questioning – one ordered Blake’s arrest. He was given permission to change, but as he came out of his bathroom, he says a male police officer punched him in the back, twisted his arm behind him and shoved him against a wall, yelling: “We need to handcuff this man – he’s resisting arrest.”

He says he was manhandled down the stairs. Blake called for help, and then for his wife to video what was going on, but the police ordered her not to film. At the police station, Blake says he was kept in the cold van for two hours, with his hands so tightly handcuffed that he says they developed weals and began to go numb. He was moved to a cell without toilet paper, bedding or basin. He says he asked for blood on the floor to be cleaned and the bright cell light – on all night – turned down, but he was mocked and the request ignored. His watch was removed, so he lost all sense of time. He was not allowed to make any calls.

It was only in the afternoon of the following day that he was interviewed by police child protection officers. They were gracious, he says, but by then he was thoroughly disoriented by lack of sleep and food. And yet, as he points out, what is said at this point is what any court case will hang on. Here the officers concluded that no action should be taken. A week later he was told the case had been closed.

Blake says his entire family has been traumatised. His children are fearful and he is shocked at his own naivety. He did not realise that such things went on in 2009. The most frightening aspect was watching other police officers close ranks when he asked them for help. You realise, he says, that these people work together and their first loyalty is to one another. What chance will your evidence have against theirs?

The Blake episode is the latest shocking example of the police using and abusing their power and their resources just because they can. Its staggering heavy-handedness and unwarranted menace echoes the Damian Green affair last year, in which a Conservative politician was arrested and nine police officers sent to comb his home, just in case he had received some minor leaks from the Home Office. There was no discretion or good judgment in either case, or sense of proportion. And in Blake’s case, once he had been defined, arbitrarily, as a potential criminal, he suddenly found himself on the far side of a terrifying divide, where he had lost all his autonomy and all rights to respect.

Stephen Cragg is a criminal barrister who says he sees many cases where the police are using too much force and too many officers when they make arrests. People are often shocked at just how roughly they are treated. At best, he says, this is risk assessment gone mad. At worst it’s a kind of summary justice. Redress is difficult. The vast majority of cases that go to the Independent Police Complaints Commission aren’t actually investigated independently, but by the forces themselves. Only 11% of all complaints are upheld. Either 89% of complainants are liars, or the system is alarmingly protective of the police.

The majority used to shrug off accounts such as these, thinking police misbehaviour was the concern of the criminal classes. But more and more of us are in danger of running up against this experience, because police powers have been so extended. As of three years ago, all offences – even littering – are arrestable. Terrorism legislation gives the police carte blanche to stop anyone. Antisocial behaviour has been criminalised. Even some senior policemen are uneasy about the consequences of acquiring so much potential authority. As one said to me: we’re like anyone else – give us power, and we’ll find a way to use it.

The rest of us, having given that power away, had better find ways to control it.

Times Recommends

• Care in old age: we won’t pay, the State can’t
• Viewers’ choice: our talentless Everyman
• Memo to the poor: go forth and don’t multiply