The Department for Education has taken a £10 million hit after selling the buildings of failed free schools to mostly private property developers.
An investigation by Schools Week found it also spent an additional £10.9 million on upkeep, such as security, maintenance and utility bills, on the empty sites.
The government revealed after a parliamentary question last year that it had sold 20 buildings due to house free schools since 2017.
A later Freedom of Information request from Schools Week showed the it had spent £131 million snapping up 16 of the sites for which it held full data.
