The Department of Health's plans to end a scheme providing free milk for under-fives have been ruled out by No 10.
David Cameron's intervention was confirmed by a Downing Street spokesperson, who said: "As the prime minister has emphasised, protecting those most in need will always be this government's priority."
The spokesperson pointed out the free milk scheme had been in place since the Second World War. "Any plans to do away with that have been ruled out," he added.
It followed the publication of a letter from public health minister Anne Milton to her Scottish counterpart revealing the plans, which had triggered memories of Margaret Thatcher's 1971 decision to end free school milk for under-sevens.
The nursery milk scheme is the only remaining element of a wartime package designed to help pregnant mothers.
"I am aware that abolition of the scheme is likely to be highly controversial, particularly as this will affect children in low-income families," Ms Milton wrote.
She said the "contentious" move would result in opposition from "the media, parents, nurseries, childminders and the dairy sector".
"However this should not prevent us from ending an ineffective universal measure - and this would clearly be the best time to do it given the state of the public finances and the need to make savings," Ms Milton added.
The closure of the free milk scheme will not now go ahead, despite the Department of Health proposing compensating for the winding-up of the scheme by boosting the value of the Healthy Start voucher.
Higher education minister David Willetts had been defending the decision on The Andrew Marr Show when news of the prime ministerial intervention broke.
He responded: "We have an endless process of assessing options. Of course it's inevitable as you go through these decisions some options are looked at and some options go ahead and some others don't. That's how decisions are taken."