The closure of schools during the first lockdown combined with disruption to community health services created a “legacy of abuse and neglect” that local authorities are still responding to, Ms Spielman said as she launched Ofsted’s annual report.
Recent reports from the watchdog suggest that children hardest hit by nursery and school closures have regressed in basic skills and learning.
Youngsters have lapsed back into nappies and forgotten how to eat with a knife and fork, while older children now lack “stamina” in reading and writing skills.
Many children did not do their school work or did very little during closures because they did not have the technology or space to work remotely.
There were also warnings of an increase in eating disorders and self-harm.
It comes as the number of children being home-educated has risen by an unprecedented 38 per cent. An estimated 75,000 children are now being home-schooled.
But there are fears that many parents have removed their children from school because they are worried about coronavirus, and that a significant number of these pupils are vulnerable. Schools were closed in March except to vulnerable pupils and children of key workers.
They reopened in September but Ms Spielman said during that time the number of child protection referrals made to local authorities plummeted and has still not returned to pre-lockdown levels, raising fears that abuse could now be going undetected.
She said: “Teachers are often the eyes that spot signs of abuse and the ears that hear stories of neglect. Closing schools didn’t just leave the children who, unbeknown to others, suffer at home without respite, it also took them out of sight of those who could help.
“When nurseries and schools closed in March, they were told to remain open to the most vulnerable, which of course meant those whose need was already identified. But we know that relatively few actually attended. The rest stayed at home – some, inevitably, in harm’s way.”
Today’s Ofsted report warns that some children and families in need of early help and protection have not been identified due to low numbers attending school during the first lockdown, combined with disruption to community health services.
Ms Spielman said it is imperative agencies prioritise the most urgent cases. The report said: “A big concern for us during the period when schools were closed to most children was the lack of visibility of vulnerable children. Schools are crucial to children’s safety and welfare, and not just while they are on school premises.”
It comes after the Standard carried out a special investigation into the impact of lockdown on children, which highlighted the plight of children living in violent homes.
The Standard also revealed face-to-face visits by children’s services in the three months to June 30 plummeted by up to 75 per cent in some boroughs compared with the same period last year. School inspections were suspended in March but are expected to restart next year.
Today’s report said 93 per cent of London state schools are good or outstanding compared with 86 per cent nationally. For primary schools the figure is 94 per cent, and for secondary schools it is 88 per cent. Only 94 per cent of London childminders were rated good or outstanding, below the national average of 96 per cent.