For how long each year is UK electricity demand at or near its peak?

Thanks to the National Grid's Gridwatch site, it is possible for anyone to download and analyse electricity consumption over any of the last 7 years.
I did it for the winter of 2015/16.
I discovered:
The peak demand last winter was 52.17GW
The demand was over 50 Gw for only 7.5 hours
The demand was over 48 GW for only 50 hours
The demand was over 45 GW for only 186 hours
We could make a good start by saving ourselves £16 billion in capacity costs by reducing consumption slightly for the seven and a half hours that demand is over 50 GW.
I will shortly be showing you an easy way to do this!
You won't have to watch the gridwatch site the whole time - a computer will do it for you!