The United Kingdom's National Transmission System (NTS) is the network of gas pipelines that supply gas to about forty power stations and large industrial users from natural gas terminals situated on the coast, and to gas distribution companies that supply commercial and domestic users. It covers Great Britain, i.e. England, Wales and Scotland.

The transmission network is owned by National Gas, which is owned by Macquarie Asset Management. Agreement was reached in July 2024 for Macquarie to buy National Grid’s final 20% stake , giving Macquarie full ownership in the first quarter of 2025.

The changing ownership of the NTS reflects developments and corporate changes in the UK's gas and energy industries.

The system originated in the construction during 1962–3 of the 200-mile (320 km) high-pressure methane pipeline from Canvey Island (on the Essex coast) to Leeds. Imported liquefied natural gas (LNG) from Algeria was turned into gas at the Canvey terminal and supplied to the pipeline, providing eight of the twelve area gas boards with access to natural gas. The gas was initially used to manufacture town gas, either as a feedstock in gas reforming processes or to enrich lean gases such as that produced by the Lurgi coal gasification process.

The pipeline was 18-inch (460 mm) in diameter and operated at 1,000 pounds per square inch (69 bar). The pipeline had 150 miles (240 km) of spur lines, supplying gas to area boards.

The Gas Council was responsible for this £10 million co-operative scheme and the construction details were a joint effort of the distribution engineers of the area boards.

LNG had first been imported to Canvey from Louisiana in February 1959, and piped to Romford gasworks as feedstock to a reforming plant.

Natural gas was discovered on the UK continental shelf in 1965 and production started in 1967. The development of offshore natural gas fields is shown in the following table. Shore terminals were built to receive, process, blend and distribute the gas.