Theresa May is facing a rebellion by Tory MPs over the energy price cap that she announced in her party conference speech.

Ministers said last autumn that prices could be capped until 2023, under plans which Mrs May said were necessary to fix the “broken energy market”, and the bill is due in the Commons today.

The government is pursuing an absolute limit on prices set by the regulator Ofgem. This comes despite pressure from backbench Tories led by John Penrose for a relative cap, on the difference between a supplier’s most and least expensive deals.

Sources suggested that the decision to introduce an absolute cap meant that loyal consumers stuck on default tariffs will lose out when the wholesale price falls. The Times understands