The former name of the licensed gas transporter that owns and maintains the gas national transmission system (NTS) which extends to England, Wales and Scotland and is the gas system operator (SO) for Great Britain. NGG was renamed National Gas Transmission following National Grid plc disposing of a 60% interest in January 2023. For more information, see Practice note, Downstream gas industry: overview.

For more information on National Grid's role in the electricity sector, see Practice note, Electricity industry: overview.