I don't think so - I think they ran trials.
This tweet suggests they're not taking any more sign-ups right now
As above - maybe try the Hugo or Loop apps.
It will generally be with your electricity supplier, so check their website out, but it's also been via the smart meter monitoring apps such as Loop and Hugo.
Loop - https://loop.homes/turn-down-and-save/
Hugo - https://hugoenergyapp.co.uk/#winter-cashback (turn it on in app settings)
I believe all the ones before yesterday (we did a few with Loop Energy) were trial events to gather data on how many people would participate and how usage patterns changed.
Yesterday was the first *real* National Grid event.
No mention yesterday from what I can see, but today is another "Demand Flexibility Service event" from 4:30 - 6:30pm whereby you will get paid for reducing electricity consumption compared to your average usage.
A message from Hugo Energy suggests the saving today is £5.46 per kWh saved. Given...