This morning, Ofgem announced another reduction in the energy price cap from July. The new cap on the unit price of energy should see costs fall by another 7 per cent, taking £122 off the average household bill. And it didn’t take long for both the Tories and Labour to try to swing the news in their electoral favour.

Only two days into an election campaign, the government will want to claim credit for today’s news: an opportunity to remind voters what successive Conservative prime ministers did to protect people from higher energy costs (of course, the Energy Price Guarantee was...