[tonylemesmer]

I agree with you that "always accurate" is an optimistic statement but I wouldn't say any level of accuracy from that note is implied. A well engineered solution would take the 5million figure as an average over a longer period of time as stated.

When I first discovered that this was how grid demand was managed, stood in a UK National Grid control centre next to my brother who was interning for them, I was amazed.

[teh_klev]

Yes, I was under the impression this would be automated. I'm sure many parts of demand management probably is, but the manual intervention involved to keep things under control during simultaneous mass tea breaks surprised me hugely.