Almost two million infants will be fed at their primary school at no cost to their parents from this week under the Liberal Democrat policy, saving families up to £400 per year.
But critics have argued the money should be used in the classroom instead and council leaders have claimed that local authorities and schools are being forced to raid existing budgets to ensure that the plans goes ahead.
Mr Clegg said providing lunch for every five to seven-year-old at England’s 16,500 primary schools will be more beneficial than some attempts to boost academic achievements. He said: “The evidence, and this has been exhaustively analysed, piloted, examined, is that giving a healthy hot meal at lunchtime is as, if not more, effective than many of the, say, literacy and numeracy initiatives which have been undertaken in the past in the classroom.”
As the programme was launched, Mr Clegg vowed not to let critics “cloud” his goal of creating a level playing field for all children, adding that the scheme is “one of the most progressive changes to our school system for a long time”.
Earlier this year, the policy sparked a coalition row over the expense of the reform, with former education secretary Michael Gove and schools minister David Laws later writing a joint article insisting they were both behind the scheme.
A new poll published by the Local Government Association (LGA) said councils and schools were being forced to raid existing budgets to ensure free school lunches to infants were available.
The Government provided £150m to cover the cost of bringing school kitchens and dining facilities up to scratch.
However the LGA’s survey of 75 councils found that nearly half (47 per cent) said they had not received enough money from the Department for Education (DfE).