ScottishPower vs British Gas

ScottishPower and British Gas are the two names most often weighed against each other by households that have never switched, and the comparison turns on ownership, service record and price rather than on anything either company does to the wires and pipes. British Gas is the biggest energy supplier in Great Britain and Britain's oldest, while ScottishPower occupies the sixth and final spot in the UK's big energy suppliers list and serves around five million households and businesses across Great Britain¹.

The two are frequently confused because British Gas trades under the name Scottish Gas north of the border, and both sit inside larger international groups: British Gas is a retail brand of Centrica plc, and ScottishPower has been a subsidiary of the Spanish utility company Iberdrola since 2007². Neither is an independent British company, and neither generates the gas or electricity a household burns in any meaningful sense of the word.

On service, the independent evidence is unflattering to both. Which? gave British Gas two stars out of five for every category its customers rated, and it finished at the bottom of the ranking table alongside EDF Energy and ScottishPower⁶. Ofgem's July to August 2025 survey found Scottish Power had a significantly lower than average proportion of customers satisfied or very satisfied overall⁷.

What each company offers in the UK

Both supply gas and electricity to domestic customers across Great Britain, and both are members of the group traditionally called the Big Six, alongside E.ON UK, Scottish and Southern Energy, RWE npower and EDF Energy². The Big Six label is historical rather than regulatory, but it still describes the shape of the market these two occupy.

British Gas operates three retail brands under Centrica plc: British Gas in England, Scottish Gas in Scotland and Nwy Prydain in Wales². That means a household in Glasgow searching for ScottishPower may in fact be looking at a British Gas account under a different name. The Energy Ombudsman notes that Scottish Gas matches the company name written on the account holder's bill, which is the practical test for anyone unsure which company they are actually disputing with⁹.

ScottishPower is headquartered in Glasgow and runs its customer-facing operation at www.scottishpower.co.uk¹. The Energy Saving Trust records that it was the first energy company in Great Britain to generate 100% green electricity, a claim about its own generation rather than about the electricity every customer receives⁸. Its fuel mix disclosure shows gas at 59% and other sources at 5%⁴.

British Gas has moved into home technology as well as supply. The company has said it is pleased to be bringing plug-in solar technology to its customers, following a government announcement that households can save as plug-in solar panels come to market¹⁰. That is a product line rather than a change to the supply business, but it signals where the larger supplier sees household demand heading.

For households in Scotland, Home Energy Scotland provides free and impartial advice funded by the Scottish Government, and acts as a referral partner for eligibility enquiries on area-based schemes¹¹. That advice is independent of both suppliers.

Specifications: what is actually being compared

There is no product specification to compare in the way there would be for a boiler. A domestic energy supply is a contract for gas and electricity delivered through national networks, and the meaningful variables are tariff type, payment method, meter type and the service standards attached to each.

The bill assumptions behind published comparisons matter here. British Gas, Scottish Power and SSE figures have historically been based on Ofgem's industry standard consumption rates of 13,500 kilowatt hours of gas and 3,200 kilowatt hours of electricity¹². A household using materially more or less than that will not recognise the headline numbers, whichever supplier it is with.

What the service record shows

Customer service is where the two are most often compared, and the independent evidence is consistent across several years. Which? reported in January 2026 that British Gas, EDF Energy, Ovo Energy and Scottish Power each received just two stars out of five for every category their customers rated, including customer service and value for money⁶. The same research placed British Gas, EDF Energy and Scottish Power at the bottom of the ranking table with overall scores below 60%⁶.

That follows an earlier Which? assessment in January 2024, which found British Gas remained the biggest energy supplier in Great Britain but that its customers' feedback resulted in mediocre scores across the board³. The pattern is not new.

Ofgem's own survey work points the same way. In the July to August 2025 findings, Scottish Power and OVO Energy both had significantly lower than average proportions of customers who claimed to be satisfied or very satisfied overall⁷. There is one countervailing official finding: in the July 2024 wave, British Gas, Scottish Power and Utilita saw a statistically significant increase in the proportion of consumers who said they were satisfied or very satisfied with customer service compared with the previous wave¹³.

Citizens Advice publishes supplier-level customer service ratings, and ScottishPower's own published results for January to March 2026 record a score of 2.94 out of 5 overall, ranking fourth among large suppliers, with results excluding Northern Ireland⁸. Both figures are given here because the discrepancy is unresolved.

What it costs, and why the cap is not a supplier price

Neither company sets the price cap. Ofgem sets it, and it applies to default tariffs regardless of which supplier holds the account. What differs is the regional level and the payment method, not the company name on the bill.

The clearest recent figures are for gas in Scotland, where both suppliers compete directly. For 1 July to 30 September 2026, the benchmark maximum gas charge in Southern Scotland on prepayment was £101.64 standing charge and £730.78 annual bill at 9,500 kWh, and in Northern Scotland £101.58 and £730.70¹⁵. On standard credit the same period gives £127.52 and £844.50 in Southern Scotland, and £127.57 and £816.45 in Northern Scotland¹⁵.

Earlier periods show how far these have moved. For 1 July to 30 September 2025, gas at 12,000 kWh per annum in Southern Scotland was £796.27 on prepayment, £820.67 on other payment methods and £886.25 on standard credit; Northern Scotland was £796.19 and £820.58 on prepayment and other methods respectively¹⁶. For 1 October to 31 December 2025, Southern Scotland stood at £119.04 at nil consumption and £804.29 at 12,000 kWh on prepayment¹⁷. Going further back, the default tariff cap for 1 April to 30 June 2024 put Southern Scotland gas at £763.74 on prepayment at 12,000 kWh¹⁸, and Charge Restriction Period 12b recorded £700.00 for Southern Scotland prepayment and £726.81 for other payment methods¹⁹. Charge Restriction Period 15b recorded £742.03 and £777.42 for Southern Scotland gas on prepayment²⁰.

Charge Restriction Period 15b gives Southern Scotland gas on prepayment as £742.03 in one table and £777.42 in another, and the default tariff cap for Southern Scotland appears as both £763.74 and £839.13 for the same 2024 period¹¹. The October to December 2025 Southern Scotland figure at 12,000 kWh appears as both £804.29 and £832.52¹⁷. Where the figures disagree, both stand.

ScottishPower's own standard variable price has tracked the cap closely: £1,477 for April to July 2026 under new TDCVs, and £1,663 against a cap of £1,664 for July to October 2026²¹. That is a supplier price, not a cap level, and it applies to ScottishPower's default tariff rather than to any fixed deal.

Company status and ownership

British Gas is a retail brand of Centrica plc, which also trades as Scottish Gas in Scotland and Nwy Prydain in Wales². It is Britain's oldest energy supplier and remains the biggest in Great Britain³. Centrica's history includes the purchase of a 20% stake in British Energy in 2011, a shareholding rather than a supply arrangement²².

ScottishPower is Spanish-owned despite the name, a subsidiary of the Spanish utility company Iberdrola since 2007, headquartered in Glasgow¹. It holds the sixth and final spot in the UK's big energy suppliers list¹. In the Smart Export Guarantee Year 5 reporting, ScottishPower submitted its annual data after the 30 June deadline, recorded as incidents in the report, and registered 14,216 installations, or 5.3% of the total²³.

Both companies appear in the Energy Ombudsman's dispute service. Scottish Gas matches the company name written on the account holder's bill, and British Gas Evolve customers should continue their dispute with British Gas⁹. The British Gas Energy Trust funds local charities and advice centres across England, Scotland and Wales²⁵. The Energy Price Guarantee, a separate support measure, applied to England, Scotland and Wales²⁶.

Neither company has failed or entered administration. Both remain trading suppliers, which distinguishes them from several challengers that have collapsed since 2021.

What this means for household energy independence

Choosing between ScottishPower and British Gas changes the name on the bill and the service experience. It does not change where the energy comes from or how exposed a household is to wholesale prices.

The UK has been strongly affected by the energy crisis due to its dependence on natural gas for heating, electricity generation and industry²⁷. That dependence sits behind the household, not in front of it, and no domestic supply contract removes it. Scotland's position illustrates the scale: oil and gas made up 92.7% of Scotland's primary energy including indigenous production and imports, and 78.0% of all energy consumption, with just 10.5% of all electricity generated from oil and gas²⁸. Scotland's rate of energy consumption is still higher than elsewhere in the UK³⁰.

There has been progress on the demand side. Scotland's domestic gas consumption fell 13% by 2024, though gas-consuming properties built in 2023 used 2% more gas than those built in 2015³¹. In 2017 Scotland was spending four times as much per capita on energy efficiency as England³². Home Energy Scotland continues to provide free impartial advice on energy efficiency and renewable energy, funded by the Scottish Government¹¹.

The historical record shows how little supplier choice has changed this. ScottishPower held 10% of domestic electricity supply by customers in Great Britain in September 2001, and the structure of the market has been contested since at least the 2001 review of domestic gas and electricity competition³⁴. Our Power, an energy supply company established by housing associations and local authorities in Scotland with the aim of reducing heat and fuel costs to tenants in their communities, was an attempt to build something different³⁵.

For a household, the practical independence available is reduction: less gas burned, less electricity drawn, and more generated on site. Switching between two large suppliers does not deliver that. The energy suppliers and household energy independence page sets out where the leverage actually sits, and the Big Six history explains how both companies came to occupy their current positions.