Ye olde Economy7 and Economy10 tariffs rely on special olde style meters which switch on secondary circuits at specified times. They are most commonly used in conjunction with night storage heaters.
As per other discussions here it seems that smart meters cannot cope with this because they do not have connections to turn on secondary power circuits.
Frankly this whole approach of having dedicated secondary circuits is unbelievably dumb and antiquated and should not in anyway be carried forward to this era of so called smart meters. ;)
To me the whole point of smart meters is that they should support much greater flexibility over tariff schemes and provide different costs for different times of day. Indeed I believe even the government mandarins - hardly known for being technically or scientifically literate want 'micro' tariffs whereby costs relate to the spare capacity on the national grid to encourage use at off peak times. Apart from night storage heaters this would allow 'innovations' like turning on your washing machine, dish washer, etc. when energy enters a cheap rate period.
To me the obvious way to do this is to have a single connection - which smart meters already support, for the smart meters to receive tariff information relating to cheap time rates over the DNO and for this to be used by smart power switches to turn devices on and off to take advantage of cheap time periods.
What we need are the smart meter makers, the generators and the distributors to work together to implement this and for them to also work with smart home system makers to produce compatible smart plugs to provide that control. Arguably existing smart plugs could be used right now as long as there was a way for this information to be passed from the smart meter to the smart home platform.
One could 'bodge' this right now if one sets a timer to match a fixed Economy tariff time schedule except one cannot use these olde style tariffs with new smart meters.
Of course this approach would mean all electricity consumed during these cheap rate periods would benefit from the lower tariff costs whereas currently only devices on the dedicated Economy7/10 circuits do so. This new approach would therefore benefit customers but less so providers.