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
The Duke and Duchess of Cambridge went salmon fishing in Canadian waters on the latest leg of their royal visit to the country.
What happens when a former president holds up a current president hoping to fly home for dinner with his family?
Following a bruising televised debate with Hillary Clinton, Donald Trump's week seems to have only got worse.