So' is it all about using electricity at the best times of the day, like my Grandmother was doing with Economy 7 fifty-five years ago without a so called Smart Meter ?
My parents bought a house in 1973 that still had the old Off-Peak metering system. There were some underhand attempts to get them to 'improve' it to the modern Economy 7, but they didn't take much persuading that they should refuse this 'kind' offer. I can't remember the exact sequence, but, instead of seven days a week all being the same, and seven hours each day being at the cheap rate, it had a few more hours in the week and lots more on Saturdays and Sundays, possibly even all day Sunday.
Another thing it had, nearly fifty years ago, was a time-switch, with a 24 hour spring back-up, that also listened to the Daventry time signal and would reset itself after a power cut, if necessary. I only found this out because I asked the bloke who came round to put 'their fuse' back in what time it ran on , winter or summer. He explained the radio situation and that, even though it might take an hour or two to reset itself at the change, it would always do it before the end of the cheap period in the morning, if there was power on. I did check it at the next time-change and, lo, it had happened.
Eventually, they were forced onto Economy 7, as their meters were 'too old and had to be replaced, but that same system was no longer available'.
I've had to deal with two people whose Economy 7 clocks were so far out that their efforts to be economical were totally fruitless.