Britain's energy supplies are secure for winter, national grid operators have said, despite expected higher gas demand at peak times and possible "tight days" for electricity.

The buffer between projected demand and supply will be similar to recent years and better than during the 2022 energy crisis, the electricity grid operator, the National Energy System Operator (NESO), said.

But like all winters, the NESO said, there may be "tighter" periods.

The annual winter outlook report comes after scrutiny of the grid operator, which was subject to alleged whistleblower concerns.

A series of once-rare summer pleas for more power were issued as the country faced numerous heatwaves.

The independent investigation into the whistleblowing allegations heard from interviewees who said the energy system on 23 June was "consistently in breach of operational limits for a number of hours" despite the NESO press release saying the system was "not at risk".

A NESO statement on Monday said the investigation concluded there "was no evidence of inappropriate influence over operational decisions or that control room records were altered or inappropriately managed in any way, including to avoid public scrutiny".

How the lights are going to be kept on

This coming winter, during times of peak demand for electricity, like particularly cold and still days when solar and wind power generation is lower, gas plants will be fired up.

This kind of gas demand - to make up for a shortfall in renewables - is forecast to increase in winter by the British gas grid operator, National Gas, despite overall demand expected to fall.

Greater use of imports is facilitating this, according to the National Gas winter outlook report, which said global supplies have a "growing importance" as liquefied natural gas (LNG) imports are forecast to rise about 6%.

The influence of 'geopolitical events' on Britain's gas

But connectedness to European and global gas markets means "external events" could influence Britain's gas market, the operator said.

"International disruptions, including geopolitical events, may affect market conditions", it added.

Supply for winter is "sufficient", however, with National Gas analysis indicating only a "rare and very unlikely" combination of events, like extreme weather coinciding with major supply disruption, would create challenges for security of supply.

Britain enters the cold months with low levels of gas stored and relying on Europe, whose own storage levels are at record lows.

Prices were unseasonably high during the typically cheaper summer months as gas generation was needed to plug power demands as Europeans turned to air conditioning and electric fans, and extreme heat made some electricity generation less effective.

Supply had already been tight due to the US and Israel's war in Iran disrupting LNG flows through the Strait of Hormuz shipping lane.

Most of Britain's imports will come from the North Sea, though domestic production declines, and from Norway.

The winter assessment was made before the government announced its approval for exploitation of the Jackdaw gas field.

If Jackdaw production begins this winter, it could "provide a modest upside to the forecast", the gas grid operator said.