National Grid’s chief executive has warned British households to prepare for blackouts between 4pm and 7pm on “really, really cold” weekdays in January and February in the event of reduced gas imports from Europe.

John Pettigrew said the company would have to impose rolling power cuts on “those deepest darkest evenings in January and February” if generators failed to secure enough gas from the continent to meet demand, particularly if the country suffers a cold snap.

Pettigrew’s comments at the Financial Times’s Energy Transition Summit came after National Grid, which oversees Britain’s electricity and gas systems, this month took the unusual step of setting out various “unlikely” scenarios in which Britain might not have sufficient energy supplies this winter.