Free school meals for every child up to seven... but how on earth in austerity Britain can we afford Mr Clegg's £600m giveaway?

• Deputy Prime Minister will announce £600m policy in conference speech
• He will claim it will improve attainment, child health and save parents cash
• Lib Dem leader boasts of deal with Tories offering marriage tax break
• 1.5 million pupils in reception, year one and year two will eat for free

Free school meals are to be extended to all infant pupils in England at a cost of £600million a year. Nick Clegg will announce today that from next September an extra 1.5million children will qualify for the meals, regardless of their parents’ income. The Deputy Prime Minister will tell the Lib Dem conference that the policy – which will save even the best-off families an average of £437 a year per child – was his price for agreeing to Tory plans for a tax break for married couples, worth about £150 a year. Scroll down for video

Free: Lib Dem leader Nick Clegg and wife Miriam Gonzales visited a school ahead of an announcement of free lunches for four, five and six year-olds in England

Not impressed: As the Cleggs around healthy fruit snacks to pupils at Lairdslands Primary School, six-year-old Dylan Hogg turned his nose up at the apple, grapes and strawberries Last night there were concerns over the cost of the scheme, while critics swiftly branded it a ‘gimmick’. Treasury sources said it would be funded through spending cuts elsewhere, but critics questioned the coherence of offering free school meals for all young children, while taking the axe to other universal payments such as child benefit for the better-off. One senior Tory said it was ‘an appalling waste of £600million of taxpayers’ money’ and a ‘deal done on the back of a fag packet’. Mr Clegg’s announcement at 5pm came only two hours after Treasury Chief Secretary Danny Alexander had told the conference: ‘There’s no spending bonanza around the corner.’ Currently, free school meals are limited to the 400,000 poorest families. Extending them to all reception, year one and year two pupils is part of what the Lib Dems called a ‘straight up and down deal’ with the Tories that will mean them agreeing to a similar sum to be spent on a tax break for married couples.

Tour: The Deputy PM visited the school in Kirkintilloch near Glasgow ahead of his announcement on free meals, which will only apply in England

Mr Clegg will tell delegates in Glasgow: ‘My ambition is that every primary school pupil should be able to sit down to a hot, healthy lunch. ‘Over the course of a year, families spend over £400 on lunch money for each child. I am determined to do all we can to help put money back in the pockets of these families. 'The Conservatives . . . have made it clear that their priority is to help some families over others, with a tax break for married couples. A tax break for some, funded through the taxes of others. ‘That tells you everything you need to know about their values. We, however, will help all families in these tough times, not just the kind we like best.’ But Tory sources dismissed the idea of a ‘deal’ over marriage tax breaks, pointing out that the Coalition Agreement struck in 2010 committed the Lib Dems to abstaining on that issue.

Healthy: Mr Clegg will argue that pupils who have school meals are healthier and achieve more academically

Learning: Pupils who eat a free school meal were two months ahead of children who did not in pilot schemes

Visit: Mr Clegg was joined by wife Miriam on meeting children at Lairdlands Primary School, in Kirkintilloch near Glasgow

Announcement: The Lib Dem conference draws to a close in Glasgow on Wednesday

Restaurateur John Vincent proposed free school meals in a review for the Government earlier this year. Mr Vincent, co-founder of the Leon chain, said: ‘I am in Ethiopia right now, and frankly I cried when I heard. This is ground-breaking stuff.’ But former Labour welfare minister Frank Field said the money could be better spent on support for disadvantaged children before they reached school age. ‘If one was looking for ways to ensure every child fulfils his potential, this would fall early in the debate,’ he said of the meals policy. ‘This has more than a little of the smell of 1950s political gravy about it.’ In pilot areas where free school meals have been extended to all, including County Durham and parts of London, students were found to be on average two months ahead of peers elsewhere.

Quite the likeness: A bust of Nick Clegg is finished by a 3D printer at the Microsoft stand at the Lib Dem Party Conference at the Scottish Exhibition and Conference Centre in Glasgow Ryan Bourne, of the Centre for Policy Studies think-tank, said: ‘There was me thinking we had huge public borrowing. 'The poorest children are already eligible for free school meals – the main beneficiaries of this new universal benefit will be middle and upper-income households, who really don’t need a public subsidy.’ Robert Oxley, of the TaxPayers’ Alliance, blasted the move as a ‘conference gimmick’, while Mark Littlewood, of the Institute of Economic Affairs, said: ‘This is an enormously bad use of public money.’ However, Save the Children’s director of UK poverty, William Higham, said: ‘This will have a huge impact on the lives of tens of thousands of children in England. For many children, a school meal will be the only decent hot meal they get.’ The National Union of Teachers said pupils of all ages should qualify, adding: ‘Children do not stop being hungry at seven.’