..private sector is forecast by the OECD to run a surplus - an excess of income over spending - of 10 per cent of GDP this year.

Obviously by "private sector surplus," he means profits, not economic surplus (=the amount of wealth created).

On a consolidated basis, the UK's private surplus funds nearly 90 per cent of the fiscal deficit.

..and profits are savings and all savings come from profits. Not from labour. The solution: Increase profits, so that public sector can take more debt and fix the economy.
Sorry, but it does not work that way.