Ofgem has instructed National Grid to revise the rules of the Supplemental Balancing Reserve (SBR) service for winter 2016-2017, so that it will be available 31st October.
The SBR is designed to support in balancing the system should there be insufficient electricity capacity in the market to meet the demand. This is classed as a last resort as it targets generators that would generally be unavailable to the market, mothballed or otherwise closed.
Ofgem announced their decision on 28th October and stated that it was necessary because of the exceptional change in circumstances, namely being that National Grid have announced that there will be reduced availability today from British and French power stations, not to mention the 3GW rise in peak demand due to the clocks going back.
Since the generators under the scheme are only paid for the utilisation of the scheme (not for the availability) this will not cost consumers anything unless the SBR is called on.