It is the second such request made in as many days by National Grid, which is responsible for ensuring supply and demand are balanced in Britain's energy systems.

"We've withdrawn the electricity margin notice (EMN) for this evening (Thursday), as our buffer of spare capacity has been restored to an adequate level,"

National Grid had previously requested an extra 466 megawatts of capacity during 1630-1830 GMT on Thursday.

A similar notice was also issued but then cancelled for the same time on Wednesday this week.

Wind power output has fallen in the last few days, while several of the country's nuclear reactors and gas power plants are also offline.

(Reporting by Susanna Twidale; Editing by Edmund Blair and Emelia Sithole-Matarise)