National Grid is responsible for ensuring supply and demand are balanced in Britain's energy systems.

"The electricity margin notice for this evening has been cancelled as our buffer of spare electricity capacity has been restored to an adequate level," a National Grid Electricity System Operator spokesman said via email.

"As we get closer to real time our forecasts become more certain, both in terms of predicted demand for electricity, weather and known generator availability, meaning our required level of reserve reduces to more accurately reflect the current conditions," he said.

National Grid had issued the EMN after forecasting tightness in electricity supply from 1630-1830 GMT on Wednesday amid strong demand, low output from wind farms and with several other power generators offline.

EDF Energy earlier said it would fire up its West Burton A coal plant if needed.

"Both West Burton A units have come on as planned," an EDF Energy spokeswoman said via email.

(Reporting by Susanna Twidale in London and Nora Buli in Oslo, editing by Louise Heavens)

By Susanna Twidale and Nora Buli