[MagnumOpus]

The utility will bill the 40p/kWh to its industrial customers (and residential customers on “agile” smart meter tarriffs), and the customers can decide whether they need the power even at 40p, or whether they shut down their bitcoin mine/aluminium smelter/EV charger/floodlights for those two hours.

In the longer term, price spikes like this incentivise the building of batteries - which might be marginably profitable most of the time but profit big time (and help big time) in periods of price spikes.