The Children's Society has warned that large numbers of children in poverty are missing out on free school meals.
The charity found that in 57 constituencies across England, more than six in 10 children in poverty were not getting a free school meal.
The constituencies of Horsham, and Bognor Regis and Littlehampton both had the highest proportion of children missing out on the free school meal at 69%.
They were followed closely by Mitcham and Morden, and Arundel and South Downs at 68%.
Only 22 of England's 533 constituencies had fewer than 10% of children in poverty missing out on free school meals.
Children's Society warned that that once parents had paid for school meals, they were left struggling to provide other basic necessities for their children, like school shoes and home heating.
In a survey of teachers by the charity, nearly half said they often saw children going hungry in school. Children's Society said the free school lunch could be the only proper meal in the day for a child of poverty.
It is calling on the government to make free school meals available to all children in poverty.
Matthew Reed, our Chief Executive, said: "It is shocking that huge numbers of children in poverty across the country are missing out on a free school meal. Every child in poverty should be entitled to this vital support.
"We know from the families we work with up and down the country that parents are struggling to make ends meet.
"Right now, the government is reconsidering which children will be entitled to get free school meals.
"We urge the government to take this opportunity to make sure all children in poverty can get a free school meal."