John Key's preparing to leave a legacy which strikes right to the heart of New Zealand identity.

Massey University's Grant Duncan says Mr Key will use three avenues to forge his legacy.

Those are New Zealand's commitment to fighting ISIS, the marking of the ANZAC centenary at Gallipoli, and the future of our flag - which he has staked some political capital on.

"He wants to lead this debate and I think he would like to leave us with the legacy that he has seen us through these important national identity and security sort of issues."

John Key is set to outline the Government's priorities for the year ahead when Parliament resumes today.

Deputy Prime Minister Bill English says social housing, Resource Management Act reforms, and the balance of intensive farming and freshwater quality will be high on the programme.

He says work in 2015 will all be aimed at keeping the economy growing and keeping New Zealand in good shape.