The recent budget coupled with market forces, are quickly bringing parity between EV charging and IC costs. Those who bought their EV's a few months ago expecting to enjoy a fuel cost advantage will soon lose that advantage if the trend follows on in this direction - driving charging costs above that of filling up with diesel or petrol.
It depends what car it was replacing... I now use my EV instead of my Range Rover as a daily. The cost per mile is about a tenth of that of the Range Rover. A lot cheaper than my +8 too. No servicing costs either.
Electricity would need to rise to £1.40 per kWh (currently 22p) to have parity with the V8's. And that assumes the cost of petrol would remain where it is now.