Since October, anyone on the Agile tariff would have paid the maximum tariff almost constantly due to soaring wholesale gas and electricity prices. Octopus currently recommends consumers to choose different packages.

Yet Greg Jackson, its chief executive, is still a keen proponent of “time-of-use” pricing, which he says will lower costs for everyone, even if only some people opt in.

He compares the system to reduced ‘yellow label’ foods in supermarkets, saying that when there is abundant energy available at less busy times, people should be able to take advantage of cheaper prices.

“Using the system when it’s underutilized,” he adds, “makes it cheaper for everyone because you’re not increasing demand for electricity at peak times.”

However, he argues that consumers should not be forced into adopting such tariffs and that caps should be in place to protect against “wild swings”.

Martin Young, energy analyst at Investec, agrees. He heats his house with an electric heat pump and is a former Agile customer of Octopus. Young “did his homework” before signing up and wouldn’t necessarily recommend the tariff to households that don’t track their energy usage closely.

“I think you have to be pretty energy efficient,” he says. “Suppliers need to help people understand the risks.”

Holt, however, questions whether it is fair to expect households to change their behavior.

Those concerns have been echoed by Citizens Advice in the UK, which says rising prices could penalize people who use medical equipment around the clock or those with older, less efficient devices.

Nor is the evening peak demand due to everyone deliberately using electricity at the same time, Holt argues, but an inevitable result of most working 9-to-5 jobs.

“The notion of surge, where you ask a single mother of three to change her behavior, when it’s not possible – you just ask her to pay more. And that’s just plain unfair.

It’s a dilemma ministers will have to think about when considering how – and if – to introduce peak prices in Britain.