A significant drop in the number of child sexual abuse cases reported to police during lockdown masks the true extent of what's happened to vulnerable children, police chiefs say.
National Police Chiefs Council data shows reports in England and Wales fell by 25% between April and August, compared with the same period in 2019.
But officers told BBC Newsnight this does not represent the true picture.
And senior officers are warning child protection referrals will now rise.
Chief Constable Simon Bailey said he suspected the 25% fall was "a false and misleading picture" of what children may have experienced during those months.
"Those children that would have been exposed to those adverse experiences during lockdown, it is only going to emerge when they spend time within the safe environment of a school, in contact with their teachers, who are very, very good and adept at identifying those signs - the indicators that something is not right within that child's life," he said.
Supt Chris Truscott, of South Wales Police, agreed there were limited opportunities during lockdown for vulnerable children to disclose harmful behaviour, which would start to come to light only now schools were back.
He too expected an increase in referrals officers would have had no way of identifying during lockdown.
"If they were vulnerable before the pandemic, then the likelihood is that vulnerability will have increased over that period of time," Supt Truscott said.
"So I think what we are likely to see is that trickle effect turning more into a river type effect where all of that six months of lockdown experiences which children perhaps have been through [are] aired."
Supt Truscott is the national police lead on Early Action Together, a multi-agency programme in Wales that aims to stop those with adverse childhood experiences (ACEs) - such as living with domestic abuse, divorce, a parent with addictions or in prison, and physical or sexual abuse - entering the criminal justice system.
Those who have ACEs are:
- 14 times more likely to be victims of violence
- 15 times more likely to commit violence against another person
- 20 times more likely to be jailed as adults
At Pencoed Comprehensive, in Bridgend, assistant head teacher Rob Green said staff training in how pupils' behaviour could indicate traumatic experiences outside school had helped vulnerable children progress.
Exclusions are down by almost 60% and attendance has risen.
But Mr Greene added: "Because of what has happened and the changes families have had, maybe losing jobs, some families that now have to make do and go without because of the economic climate we are in, the pressure within the family will increase.
"So I do think we will have a lot more support we will need to put in place and we will be supporting our pupils as best we can."
In England, meanwhile, those responsible for child protection are concerned there is not yet the same integrated approach.
Mr Bailey, who heads the Norfolk force, said England had "some work to do" putting in place the right joined-up policy.
"It needs to be the golden core that is woven through the fabric of everything that we do, be it in the police service, be it in the Ministry of Justice, be it in the Department for Education, the Department for Health," he said.
"We all have a responsibility to ensure that future generations of children have the opportunity to succeed and to thrive.
"And if we get this right, and the golden core of safeguarding and caring for children and nurturing children, so they can optimise all the things that are going for them, then actually we will take a significant step forward."
The Department for Education said it had invested funds to support vulnerable children.
And its advice for schools was clear: "Continue to identify and report any incidences of abuse or harm."
"We are placing social workers in schools to help spot the signs of abuse and neglect more quickly and work with teachers to support children at risk," it added.