Customers will be asked to limit their use of electricity and gas for two hours after temperatures plummeted as low as -15.6C.

The National Grid is running a planned test which will see households paid to cut their energy use between 5pm and 7pm - the period in which record prices are expected during peak demand hours.

Octopus Energy, Drax and Eon are all taking part in the scheme, in a bid to avoid potential blackouts throughout the rest of the winter months.

So far, National Grid's Electricity System Operator wing has run four one-hour trials of the so-called demand flexibility service. But tonight will mark the first two-hour session.