Boris Johnson must show he is serious about vulnerable children by placing them at the heart of his plans to ‘build back better’ post-Covid, England’s children’s commissioner has said.

Anne Longfield warned that the Prime Minister’s promise to “level up” the country will be “just a slogan” unless children are put at the “centre stage”.

In her final speech in the post, Ms Longfield called for a new “Covid Covenant” of education and wellbeing support in every community to help children and young people recover from the pandemic.

A year of opportunity should be launched once the virus is suppressed where schools, sports halls and swimming pools are used at evenings, weekends and holidays to help pupils “catch up with confidence”, she said.

Ms Longfield called on Mr Johnson to get “passionate” about making sure that children are not defined by what’s happened during this year but “instead that we define ourselves by what we offer them”.

The machinery of Government means that so many who are responsible for decisions about children’s lives don’t get to meet them

“It will take political will and funding – an opportunity fund – measured in billions, but it would be worth every penny. It should be led by the Prime Minister,” she said.

The children’s commissioner accused the Treasury of “institutional bias against children” as only just over £1 billion has been committed to pupil catch-up support despite warnings from the Institute for Fiscal Studies (IFS) that school closures could lead to a loss in earnings of £350 billion in the long run.

Ms Longfield, who will be replaced by academy chain leader Dame Rachel de Souza, will highlight uncertainty about the uplift in Universal Credit.

She said: “Two weeks ago the Prime Minister said educational catch-up was the key focus of the entire Government – yet we still don’t know if next month he is planning to take the Universal Credit uplift away from millions of families. These two positions aren’t compatible.

“If the Government is really focused on educational catch-up, it wouldn’t even countenance pushing those 800,000 children into the devastating kind of poverty which can have a much bigger impact on their life chances than the school they go to or the catch-up tuition they get.”

This is how children fall through the gaps – because too often the people in charge of the systems they need simply don’t see and understand their world

The children’s commissioner added: “It’s impossible to overstate how damaging the last year has been for children – particularly those who were already disadvantaged.

“‘Building back better’ must mean rethinking our priorities and the way we care for children in this country and to do that we must be honest about the scale of the challenge and face the tough questions about the gaps that we know exist.

“How many children are in families that are struggling to support them; how many are starting school so far behind they’ll never catch up; how many children with mental health needs or special educational needs aren’t getting the help they should be?”

Ms Longfield, who reflected on her six years as children’s commissioner, talked about her frustration with Whitehall officials failing to tackle many problems facing vulnerable children.

In her speech, she said: “The machinery of Government means that so many who are responsible for decisions about children’s lives don’t get to meet them. Instead the Government machine seems to view them as remote concepts or data points on an annual return.

“This is how children fall through the gaps – because too often the people in charge of the systems they need simply don’t see and understand their world.”

“Too often I have had to cajole people to the table, to watch them sit through a presentation, maybe ask a question, and then on too many occasions almost vacantly walk away going back to the task and the priority of the day.

“I don’t believe that truly reflects the extent of Government and the public’s commitment to helping children succeed,” Ms Longfield added.

Ms Longfield, who will step down from the role at the end of the month, called it a “national scandal” that almost a fifth of children leave school or college without basic qualifications.

She called on politicians not to forget vulnerable children, adding: “These are your children now. You have a chance to put them centre stage. When you do build back better, make sure you do it around them.”

During the virtual event, Tory MP Robert Halfon, the chairman of the Education Select Committee, said the Covid-19 pandemic had “laid bare the damning truth about our educational divide”.

He said catch-up support for children should “not just be about algebra and Shakespeare” as children’s mental health had become “dangerously fragile”.

An extension of the school day – for physical activity, mental health support and tuition – would support children’s “broader recovery,” Mr Halfon said.

A Government spokesperson said: “Protecting vulnerable children has been at the heart of our response to the pandemic, driven by our commitment to level up opportunities and outcomes.

“That’s why we have enabled the most vulnerable children to continue attending school in person, while providing laptops, devices and data packages to those learning at home and ensuring the most disadvantaged children are fed and warm.

“We have also driven forward crucial reform in adoption, in the care system, in post-16 education and in mental health support – and our long-term catch-up plans and investment of over £1 billion will ensure we make up for lost time in education over the course of this Parliament.

“Anne Longfield has been a tireless advocate for children, and we’re grateful for her dedication and her challenge on areas where we can continue raising the bar for the most vulnerable.”