@cupotee2
The last time I had Economy 7, the entire thing was under radio control and a small box, next to the meters would emit a loud "k-clack" noise, late at night.
Due to a sleep disorder, I would often catch this thing switching back to full price electricity at 3am. I challenged my electricity provider about this and, whilst the telephone operator said this was 'normal' under contract terms and to discourage the widespread use of washing machines at night (a known fire hazard, alledgedly), the practice ceased, soon after.
The storage radiator only had two controls: a charging rate control and a vent control. It had a switch on its wall socket (30Amp grade) so I could cut its power if I felt it was charging on full-rate electricity.
The point of explaining this is that there was no "clock" attached to my electrics, in that house. It was all remotely controlled by a radio signal, sent locally. The provider said that switchover timings are "flexible", town by town and depend upon both local demand and the state of the national grid, in general. The transition from the household's use of a few lights, a TV, a computer to one or two multi-kilowatt storage heaters needs to be carefully timed.