About 10pc of the EU’s total energy demand is met by Russian gas, ranging from 35pc in Hungary to 0.2pc in Sweden, according to research by Capital Economics. Germany and Italy are among the most reliant. 

Britain only gets less than 3pc of its gas supply directly from Russia. In interconnected international markets, however, it feels the high prices along with Europe when there are shortages. 

European countries including Germany have been trying to prepare for gas supply disruption, including talk of keeping ageing nuclear or coal-fired plants open longer than planned. 

But such measures are likely to only go so far, with varying degrees of “demand destruction” – using less gas – needed to get through next winter, in particular, if Russian supplies were cut off.

“To some extent, the next few months you might be able to navigate through, but come next winter you would have no chance to get through [without demand destruction],” says Massimo Di Odoardo, vice-president of gas and LNG research at Wood Mackenzie. 

European energy think-tank Bruegel reckons the bloc would have to cut gas demand by 10-15pc without imports from Russia, which it says is possible. Industrial users are generally first in line to cut demand, as they use the most and Governments generally want to shield households. 

The European Central Bank estimated at the start of the year that a 10pc cut to gas supplies would slash output in the eurozone by about 0.7pc. This falls in line with estimates of the impact of previous energy rationing, such as in the UK in the 1970s, according to consultancy Capital Economics.

It might not just be industry that is impacted, however. “The measures in place to reduce gas demand in industry and the power sector might not be enough to keep heating at a reasonable level,” says Di Odoardo. 

The war in Ukraine is already pushing costs higher. The British wholesale gas price jumped 50pc on Wednesday to touch 463p per therm, falling back to 394p by evening – a higher level than September when its rise forced a key UK fertiliser plant to shut down, threatening crucial supplies of by-product carbon dioxide. 

“We are back at the demand destruction levels,” says Wheaton. “I think what you will see is a hierarchy – industry having to use less, that’s where demand rationing will hit first, with power generation and consumers at the bottom of that hierarchy.”