Tens of thousands of extra school places will be needed by next year amid a continuing surge in demand, the Nation Audit Office said.
Ministers will visit schools in London today to see the problem for themselves.
According to Barking Council, an estimated 1,000 extra primary school places will be needed in Barking each year, in line with projected population growth.
More top news
Simon Cowell admitted he was "so embarrassed" after his shirt burst open during an X Factor audition.
Following the promise of further powers for Scotland, David Cameron is now talking about a new deal for the other home nations.
The Suitsy: Man creates business suit onesie