Jeremy Corbyn's plans to impose VAT on private school fees to pay for free meals for all primary school pupils have unravelled after questions were raised about the evidence used to justify the policy.

The Labour leader will say this morning that the universal roll out of free meals will boost the health and educational attainment of all children while ending a "subsidy to the privileged few".

He will point to research showing that offering universal access to free school meals improves pupils' productivity, enabling primary school pupils to advance by around two months on average.