The Prime Minister's announcement on an energy cap was always going to prove a challenge. Ofgem's comments show that timing could be an issue as well but the real test will come with the publication of the draft legislation.

This could take several forms but what will tell us more is the language used about when next steps will take place and what the process for consideration of the proposals will be.

We could be looking at 'aims' rather than firm commitments. Plus the added complication of the lack of a Parliamentary majority could make this a challenging set of proposals to get passed in legislation.

Ofgem are right to be concerned about the risk of a legal challenge. The energy companies will rightly consider all their options as this is a fundamental imposition on the working of the free market. A market that a previous Conservative administration established.

This type of market intervention could upset some on the Conservative backbenches so the successful passage of a Bill is by no means guaranteed.

Mrs May grabbed some immediate headlines but the reality of delivery could bring some more unwelcome ones.