As more children rely on them nationally, the Children's Society warns that the pandemic has caused "long-term, devastating consequences" for those in low-income families.
Data from the Department of Education shows that by the end of the 2020-21 school year, 73% of Blackpool's children in need were eligible for free school meals – up from 59% at the same point in 2016-17.
A child in need is defined by the Government as a child who needs support from their local authority to maintain a decent standard of development and education.
This includes children with disabilities and special educational needs, young carers, children who have committed crimes, and those with parents in prison.
Free school meals are available to children who have parents receiving benefits or are on incomes of less than £7,400 – so an increase in the number of children on free school meals can be an indicator of declining living standards.
The pandemic coincided with a small year-on-year increase in pupils needing free school meals in Blackpool – between the end of the 2019-20 and 2020-21 academic years, 5% more children became eligible for them.
The figures cover children in need who are not in receipt of a children protection plan and are not in foster homes or adoption.
Last school year England saw the largest increase in eligibility among children in need since 2016-17, when the figures were first recorded, of 6%.
Across the country, 57% of children in this category were eligible for free school meals at the end of 2020-21, up from 45% in 2016-17.
This compares to 21% among the overall pupil population, up from 14% in 2017. In Blackpool, 39% of all pupils were on free school meals, compared to 26% in 2017.
Azmina Siddique, Policy and Impact Manager at charity The Children's Society, said that the pandemic has been devastating for low-income families.
"While some year-on-year increase in the numbers of people qualifying can be put down to certain protections in the system as Universal Credit is fully rolled out, it is also likely the increase in free school meal uptake is due to growing need" Ms Siddique said.
“Free school meals provide vital help to families – saving them over £400 per child each year – but too many families simply don’t qualify, meaning hundreds of thousands of children are missing out."
Some of the rise could be explained by protections on access to free school meals: since 2018, pupils eligible remain so for several years, even if their circumstances change, for instance if their parents no longer receive benefits.
Last year a report from the Child Poverty Action Group, a charity tackling child poverty, estimated that across the UK around 1 million children in poverty did not have access to free school meals due to high eligibility criteria.
A Department for Education spokesperson said: “We want to ensure every eligible child has access to free school meals, which is why we have expanded access to them more than any other government in recent decades.”