The UK ’s ruling Conservative Party has promised to cap energy prices , causing share prices in Centrica , which owns British Gas , to fall 4.2 % , whilst shares in Shell fell 3.2 % . Miliband joked on Sunday that the interventionist stance taken by the Conservatives would prompt criticism from newspapers that had attacked his pledge four years ago. Both companies saw similar share price drops in 2013 when former Labour leader Ed Miliband pledged to introduce an energy price freeze . Ministers have said that a cap on standard variable tariffs , paid by over two - thirds of households , would save families £ 100 ( $ 128 ) on average each year . Berenberg bank estimates that a cap would cost energy companies at least £ 1.7bn a year , with the industry 's big six firms shouldering the majority of losses .
The UK ’s ruling Conservative Party has promised to cap energy prices , causing share prices in Centrica , which owns British Gas , to fall 4.2 % , whilst shares in Shell fell 3.2 % . Both companies saw similar share price drops in 2013 when former Labour leader Ed Miliband pledged to introduce an energy price freeze . Ministers have said that a cap on standard variable tariffs , paid by over two - thirds of households , would save families £ 100 ( $ 128 ) on average each year . Berenberg bank estimates that a cap would cost energy companies at least £ 1.7bn a year , with the industry 's big six firms shouldering the majority of losses .