The BBC’s plan to keep Britain informed during a prolonged blackout rests on FM radio and communications independent of the internet, even as copper landlines approach switch-off and the government reviews FM’s future.

Around 100 BBC staff would run a special emergency radio studio, supplied with fuel, food and water for at least three days. Secure communications would not depend on the internet. Pre-arranged government messages, with scripts already published online, cover drinking water and disposing of toilet waste when flushing is impossible.

Journalists at emergency centres around the UK would send information through satellite vehicles. Transmission towers isolated from the internet have diesel generators intended to sustain broadcasts for three days. Teams would use satellite phones, with agreed procedures and meeting points if those failed too.

A BBC insider said planning originally covered five to seven days, but advice from the National Energy System Operator now suggested power could probably be restored within two to three days. That is an expectation, not a guaranteed restoration time.

The practical case for independent communications emerged in Lancaster on 5 December 2015. At 22:45, flooding of the River Lune cut electricity to 61,500 people. Some water supplies failed; the railway station, petrol stations and shops closed, while most cash machines and traffic lights stopped working.

Copper-wire telephones and FM radio survived. Local station The Bay used an emergency generator and a landline, with a reporter travelling beyond the affected area to telephone information back.

Such widespread disruption is known as a ‘Black Sky’ event. A recent UK resilience summit focused on withstanding at least 72 hours without essential systems. The government says there is no specific threat to the grid; its preparedness campaign covers several possible emergencies.

Lord Harris, chair of the National Preparedness Commission, warns that electricity failures can interrupt water pumping and cause sewage blockages and overflows. He argues that decades of efficiency measures have stripped out backup systems, and questions replacing emergency-service radios with mobile-network technology. The government maintains that modern 4G and 5G systems are resilient and reliable.

It is also spending £70 million developing high-altitude aircraft intended to provide at least a week of emergency mobile and internet connectivity. Rico Chandra, programme director at developer Enduring Atmospheric Platforms, says satellites have limits as a fallback when ground networks fail.

Copper landlines are due to be switched off on 31 January 2027. Lancaster University engineering professor Roger Kemp believes preparedness has gone backwards. The government counters that copper networks are now unreliable and difficult to repair. The unresolved issue is what will provide an equally dependable fallback when electricity and digital communications fail together.