Gonzalo Vina quoted the Sutton Trust on academies in his Financial Times story on the budget

Schools, especially in the north of England, will receive £500m in extra funding from the Budget to improve standards.

The announcement came ahead of an overhaul that Nicky Morgan, education secretary, is due to unveil on Thursday.

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Conor Ryan, director of research at the Sutton Trust, which campaigns for social mobility, said evidence of the performance of academies is mixed and that only 11 out of 34 chains outperformed the national average for attainment in 2014.

“While some chains are clearly excellent, others have seriously underperformed and have expanded too rapidly, he warned. Julie Mercer, global and UK education leader at Deloitte, the business advisory firm questioned the “leadership and skills needed to enable academies to become financially sustainable.”