Callistemon21
Elegran
Here is a link to the actual plan for sceduling powercuts, should they become necessary.
assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/995049/esec-guidance.pdf
You can find out what reference letter your house comes under from your power bill. It will be " a letter, often boxed, located near the top. Note that not every energy supplier will include your load block on your energy bills, so if this is the case you will need to contact them directly to find out." When you have this, look in the rota tables.
I just had a look at this, Elegran and it seems to be a version which was Revised in November 2019.
Surely it must have been updated since then, as other events have changed the likelihood of outages?
Of course it will be largely unchanged - the area labels will be the same as they used to be, because they define the areas controlled by master switches in the Grid control centres. The central Grid wiring and switching map has not changed materially in four years, so a rota for throwing those switches in an emergency will be as valid now as in 2019. If you can find a revised version, do post it.
I don't think it is claimed to be something new. It is not a novelty for the electricity supplies to face a threat which may cause them to have to impose blackouts and it is not surprising that a system has been devised and still exists unchanged.
I have just shown it to my son-in-law, who says that it looks very like the rota that they received from their electricity supplier during the 1970's power cuts. Plus ça change, plus c'est la même chose , except that with the internet the rota is more accessible, and earlier, now than it was in the 70's.