According to The Guardian, the British government started ‘war-gaming’ an emergency plan to deal with wide-scale disruptions to its energy supply last year, before Russia’s invasion of Ukraine. The plan, called Programme Yarrow, was initially set up to deal with impacts to the National Grid.

Yarrow lays out the government’s response in the event of a sudden loss of power across the country, impacting everything from transportation and communications to food and water supplies.

The contingency plan envisions 60% of power would be restored within two to seven days. Rolling blackouts would be implemented to ration supply. Yarrow puts a priority on restoring power to young and older residents.

According to The Guardian, the British government doesn’t want any publicity about Programme Yarrow, because they don’t want people to think it was tied to recent events like the war in Ukraine. It’s important to note the British government is not saying Britons will definitely go without power for a week. The government is just preparing for that scenario. However, by simply preparing for the possibility, the U.K. is signaling weeklong blackouts are not impossible.

Jan Rosenow, Europe director at the Regulatory Assistance Project said, “There are so many things coming together at the same time: the gas shortages, high prices, the problems with electricity generation from nuclear plants in France. That’s what causes concern in government. It is prudent [to plan for outages]. It’s a shame it takes a crisis to have this conversation.”