Fuel poverty could double in autumn 

Lewis said sky-high gas and electricity prices could last at least another year and a half, especially with the energy price cap due to rise again in October.

He warned of “unprecedented” hardship and expressed concern that the number of households experiencing fuel poverty – defined as spending over 10% of disposable income on energy bills for an acceptable standard of warmth – could double this autumn.

Chancellor Rishi Sunak is drawing up a temporary levy to ease the cost-of-living crisis, with the Treasury developing plans for a windfall tax on oil and gas companies who have been recording record profits, The Times reported.

Although unpopular with some cabinet ministers due to “unconservative” tax, a YouGov poll for the publication found the levy would be immensely popular, with seven in ten Britons in favour of a windfall tax.

Lewis said Russia’s invasion of Ukraine was to blame for most of the energy difficulties and warned customers the worst was yet to come.

“In my 30 years in energy I have never seen prices increase at this rate,” he told the BBC.

“I think for the next 18 months we’re likely to see higher prices. That’s already baked in, certainly in October and probably into next year as well. I think the longer-term development depends on what happens in the war in Ukraine, what happens with Putin. I have no idea how that will develop.”

He further commented that one million of E.On’s customers were already behind with bills and forecast this would increase by 500,000 by autumn. E.On runs about 8m energy accounts in Britain.