Grid bosses insist the lights will stay on this winter but warn of 'tight days' amid reliance on imported gas

When cold, still days cut wind and solar output, Britain will fall back on gas plants to keep the power flowing. Liquefied gas imports are forecast to rise by about 6%. The National Energy System Operator (NESO) still warns of possible 'tight days'. Whistleblowers told an inquiry the system was 'consistently in breach of operational limits' on 23 June, while NESO publicly said it was 'not at risk'.

The NESO-backed inquiry found no evidence that control room records were altered.

National Gas warns that 'external events' abroad could affect Britain's gas supply.

Heatwaves this summer brought a run of once-rare appeals for extra power.