Police have been condemned for leaving a 16-year-old girl who threatened to self-harm naked in her cell for 10 minutes and then pushing replacement clothes through the door hatch.
The girl, who was detained in Skegness, even had her complaint about being "violated" disregarded when an officer told her she would have to pursue it after her release and then didn't follow it up.
The girl had her bra removed by staff and a male officer "pushed" her twice because her behaviour was "challenging".
The details of the case were revealed in a damning report on Lincolnshire Police's custody, which Her Majesty's Inspectorate of Constabulary said her treatment was "demeaning and unacceptable".
HMIC said the force's safeguarding policies for children left it "particularly concerned", adding: "There was little acknowledgement of the vulnerability of children; they were offered no specific support or care."
Describing what happened to the teenager, inspectors noted two female staff removed her bra and then returned to the cell with an anti-rip suit, given to detainees whose clothes are removed to protect them from harm.
"Staff appeared to spend some time negotiating with the girl before she was restrained; staff then left the cell, inexplicably, taking the anti-rip suit with them, leaving the girl naked in her cell for a period of around 10 minutes," they wrote.
"At this point, the top half of the anti-rip suit was posted through the cell hatch, followed by the lower half about 10 minutes later. Her behaviour was challenging and resulted in a male officer pushing her twice while she was naked.
"The vulnerability of this girl in police custody was compounded by her being left naked in a cell. Not enough was done to maintain her dignity."
She complained the next day to a sergeant, who told an inspector but it was not followed up.
HMIC said her treatment was "demeaning and unacceptable". Though it did not specify why the girl was detained, it criticised the number of people detained under the Mental Health Act being held in police cells due to a lack of alternatives in the county.
The new Policing and Crime Bill will change the law to prevent under-18s detained under Act from being put in police cells.
Sarah Brennan, chief executive of YoungMinds, told The Huffington Post UK: “Too often young people experiencing a mental health crisis end up in a police cell because there is no other place of safety for them.
"While we welcome the change in law that will end this appalling practice, there must be funds available so that there is an increase in the number of safe, appropriate beds that local areas can access.”
HMIC said Lincolnshire Police were too quick to remove detainees' clothing when they were perceived to be at risk without thinking about their dignity.
The force insisted it had been "particularly concerned" for the girl's mental state and denied it had been negligent.
“The fact of this case is that the custody officers were concerned that she would harm herself and decided that she needed to be given an anti-rip suit. Due to the first suit being the wrong size, another was produced within minutes,” Deputy Chief Constable Heather Roach said.
“The way the report is worded implies that we were neglectful and I reject that contention. We were particularly concerned for her safety and mental state."