There are few issues more likely to stir emotions than the question of free school meals: which children should be entitled to a hot lunch at school free of charge - and if their family does not pay for it, who should shoulder the cost?

In November last year, the Government launched a consultation over proposals under the new Universal Credit system which it says will target benefits more fairly towards lower-income families. This includes a net income threshold of £7,400 a year for families whose children would be entitled to free meals - typically equivalent to between £18,000 and £24,000 in total household income per year.

The change would mean, minister for children and families Robert Goodwill said, about 50,000 more children becoming eligible for free lunches. But others, including the Children’s Society charity, warned it would still mean about one million children from poor families being left without a free meal.

There is general agreement that children behave and learn better when they have eaten properly. But it wasn't always so. When the first schemes to provide meals for poor and undernourished children emerged in the 19th century, the charities that ran them faced indifference if not hostility.

But the idea began to take hold and was given a boost when recruitment of young men for the Boer War of 1899 to 1902 highlighted widespread undernourishment, and there was a new focus on the importance of healthy eating.

Local authorities were given the green light to spend public money on school food, backed by government money, in 1906, and take-up of free and paid-for meals increased through World War Two.

Then came the birth of the welfare state ushered in by the post-WW2 Atlee government and by 1949 the number of school dinners reached nearly three million, more than half the school population. The total continued to rise and at its peak in 1974 70% of pupils ate school meals.

Since then, however, the number of children receiving school meals has been in steady decline and in the 1980s the Thatcher government cut back on entitlement and removed some of the standards designed to ensure healthy meals. The proportion of children taking school meals fell to just four in 10.

In more recent years there has been a revival of interest in making sure youngsters get a good meal at lunchtime, spurred on by the abundance of cheap 'junk food' and, perhaps, the widespread introduction of cafeteria-style school canteens. While enabling youngsters to choose for themselves what they want to eat, the possible disadvantage is that those choices may not be the healthiest.

Concern over children's diet, including high-profile campaigning by of celebrity chef Jamie Oliver, led to a revival of interest in the topic and in 2013 the Tory-Lib Dem coalition announced it would extend entitlement to all infant school children - meaning 1.5 million more pupils being entitled to a free meal.

Campaigners argue that, come the full roll-out of the Universal Credit in 2020, all those whose families are in receipt of the benefit should be entitled to a free school meal - leading to an increase of about one million children receiving the benefit.

Some argue that the system would be improved if automatic enrolment to free meals for disadvantaged children using government tax and benefit records instead of schools having to persuade parents to apply.

This, they say, means not only that many children miss out, but that pupil premiums worth about £1,000 per pupil do not find their way to the schools. A large proportion of households whose children are entitled to free meals currently fail to sign up.

The Government says its proposals will target more children from lower-earning families while not affecting universal infant free school meals which will continue to be available to all pupils in reception classes and years 1 and 2 regardless of parental income.

Waiting in the wings, Labour has pledged to introduce free meals for all primary school children and it seems certain it will remain a controversial political topic: the question at its heart is whether children should be provided with a good meal while at school courtesy of the state, funded out of general taxation, or whether those from better-off families should be made to pay.

Meanwhile most would agree that there are too many youngsters existing on a diet of crisps and chocolate who would benefit from a proper meal at lunchtime - whoever ends up paying for it.