This may illustrate some of the reasons. I assume that there is a similar scheme in place for this year. Towards the end of my career in the industry I had noticed that the numbers of "Notification of Inadequate System Margins" (NISM's) had gone from zero in the 2000's to 3 or 4 a year by the time I retired in 2013. This has frightened the Government into action!
https://www.theguardian.com/environm...this-christmas