The cost of housing benefit is set to treble to over £70 billion a year by 2050 because successive Governments have failed to build enough council houses, the Centre for Social Justice (CSJ) has warned.

As the Chancellor puts the finishing touches to Monday’s “end of austerity” Budget, the CSJ warns that so-called “affordable” new homes only help the middle classes and will do nothing to reduce the burgeoning housing benefit bill, which is forecast to hit £23.4 billion in 2018-19.

The findings come after the Prime Minister’s bid to strengthen councils’ ability to build more homes by scrapping their borrowing cap and clamping down on private developers dodging their social housing commitments.

The CSJ warns that the lack of council houses has led to a surge in the number of housing benefit recipients renting in the private sector, with the number of private renters doubling since the millennium.

A benefit recipient in the private rented sector costs the taxpayer 25 per cent more on average than one living in social housing.