National Grid has received fierce criticism after the publication of pictures showing its office headquarters in Warwick with almost all lights on after its staff went home.

It was last week that its Winter Outlook report warned Britons that in an “unlikely” scenario, homes and businesses across the UK could face three-hour power cuts because of energy shortages.

Snaps of empty offices with lights shining brightly were reportedly taken by a photographer at 7.30pm at National Grid’s Warwick headquarters.

The pictures showed that nearly all office lights were left on.

A National Grid spokesperson told ELN: “Our Warwick office houses operational control rooms for gas and electricity where engineers work in shift patterns 24/7 to keep the lights on and gas flowing across the UK.

“The building has many energy conserving measures, including sensor-controlled lighting which turns itself off automatically if a room is empty.”