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Big Six Energy Suppliers

If you’re looking for information on the Bix Six energy suppliers in the UK, search no more. Find out who they are, their origins and market share and, how they came to be the most significant energy providers and companies in Great Britain.

Who are the Big Six Energy Suppliers?

Collectively, they are known as the ‘Big Six’ as they supply the majority of households in the UK with gas and electricity. They are:

While they dominate the energy supply market, they are by no means the only companies available to consumers. Nowadays, competition for gas and electricity customers comes in the form of smaller energy suppliers, who can offer cheaper, greener or more flexible deals on fuels.

The Big 6 Energy Suppliers

The story of the Big Six can be traced back to the 1989 Electricity Act, which led to the privatisation of the UK’s Central Electricity Generating Board (CEGB). After many mergers, acquisitions and dissolutions, what was left was the Big Six as we have it today.

British Gas

Formed in 1973, the British Gas Corporation as it was known at the time, as a result of many historical gas companies and gas boards merging into one. Synonymous with energy, British Gas is possibly the most well-known gas and electricity supplier in the UK.


Powergen was one of the energy companies formed after the Electricity Act was passed at the end of the 1980s. That company now operates under the name E.ON after it was bought by E.ON AG, a German energy franchise in 2002.


Another company under German ownership, nPower is a popular gas and electricity supplier and, electricity generator. Formerly National Power and Innogy, nPower’s energy services also include repairing boilers and central heating systems.


Owned by the French Électricité de France group, EDF generates its electricity as well as supplying both fuels. It was formed in 2002 following the merger of SEEBOARD, London Electricity, SWEB Energy and later on, British Energy.

Scottish Power

Once part of the South of Scotland Electricity Board, Scottish Power now falls under the Iberdrola umbrella of companies, based in Spain. Despite its name, Scottish Power also supplies energy to many parts of England, particularly in northern regions of the country.


Previously Scottish and Southern Energy, the SSE brand name came into effect when parts of the Southern Electricity Board and the North of Scottish Hydro-Electric Board were merged. SSE’s operations also include gas storage, exploration and production, and metering.

The Big Six Market Share

The Big Six energy companies represent about 75% of the energy supply market in the UK, while smaller energy firms (roughly 60 - 70 companies) only attract around a quarter of the market share combined. In real numbers, the Big Six’s dominance can also be broken down approximately as:

SupplierMarket Share
British Gas17 million customers
SSE9 million customers
E.ON7 million customers
EDF Energy6 million customers
nPower5 million customers
Scottish Power5 million customers

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