Ed Miliband took a policy straight out of the New Labour's play-book by promising to limit classroom sizes to 30.
The pledge is a reheated version of Tony Blair's promise ahead of the 1997 general election, when New Labour secured power.
Miliband, speaking at his old school in Camden, also revealed that a Labour government would stop building "wrong-headed" free schools.
"Currently, the government is spending money on new Free Schools, in areas where there are surplus places. This simply makes no sense when class sizes are rising in the way they are. Or when people can't get their kids into the good schools they want," the Labour leader said.
"So, by ending the scandalous waste of money from building new schools in areas of surplus places, we will create more places where they are needed. This will allow us to cap class sizes for five-, six-, and seven-year-olds at no more than 30 pupils."
Miliband stressed that he wanted every child to have the experience he had of "great teaching" at Haverstock school.
But the Tories claimed that Labour policy had "collapsed within minutes" since primary school sizes are already capped at 30.
"Miliband's policy has collapsed within minutes – primary school sizes are already capped at 30," a Conservative Party spokesman said.
"Are Labour saying they will scrap sensible exceptions like those that ensure Armed Forces children get a place at primary school, or ensure that twins aren't forced apart? This incompetence and chaos shows exactly why Miliband is simply not up to the job."
The announcement comes with less than 90 days to go before the general election, with Labour one point ahead of the Tories in the opinion polls (33% vs 32%).