Generally, National Policy Statements (NPSs) make clear the Government's objectives for the development of nationally significant infrastructure in a particular sector, setting out its policies and explaining the reasons for them. They are often generic but, where appropriate, can relate to specific locations to provide a clear framework for investment and planning decisions. Also, they are subject to public consultation and parliamentary scrutiny before being designated. Once they are designated, they provide a framework within which the Planning Inspectorate (PINs) can make recommendations to the Secretary of State.

The Government published its initial draft (ANPS) and accompanying consultation documents in February 2017. It set out the need for additional airport capacity in the south-east of England, clarified the case for the preferred location and scheme to deliver new capacity and considered and supported measures relevant to a development consent application to which the Airports NPS relates.

The final version of the ANPS was delayed because of the 2017 general election so government had to relaunch a public consultation on a revised draft Airports NPS (NPS) in October 2017. The final ANPS was laid before parliament on the 5 June 2018 and was formally designated as a National Policy Statement under the provisions of section 5(1) of the Planning Act 2008 on the 26 June 2018, paving the way for Heathrow to now submit a formal planning application, a Development Consent Order (DCO). The final version of the ANPS is available from: https://www.gov.uk/government/publications/airports-national-policy-statement

In the meantime, the London Mayor, some London Councils and environmental activists such as the Greenpeace and Friends of the Earth have submitted a legal challenge to the high court after the ANPS  was approved by the government.