A Capacity Market Notice was issued on 31 October for the first time. The notice – which this year covers just a small amount of demand side response – was raised at 12.06pm for 4.30pm and at 6.53pm cancellation was announced from 7pm.

National Grid had already been granted permission by Ofgem to call on its Supplementary Balancing Reserve (SBR) plants on 31 October if required. It had to get permission from the regulator because the SBR was not due to go into operation until 1 November.

The System Operator sought that permission on 27 October, in response to expected low capacity availability in France (where several nuclear units are in outage while safety checks are carried out on major components) and in GB, at the same time as there was limited availability on the east-west interconnector with Ireland, which is undergoing maintenance. This coincided with the first working day when – because the clocks changed at the weekend – the lighting up and tea-time peaks coincide, adding 3-4GW to peak requirements.

Permission was granted on 28 October. SBR plants did not receive availability fees for 31 October.