Q&A: Energy tariff row

Four of the big six energy companies have announced price rises in recent weeks

As many UK households face the prospect of rising energy bills, politicians are engaged in a row over exactly what help will be available for consumers.

At Prime Minister's Questions, David Cameron said: "I can announce... that we will be legislating so that energy companies have to give the lowest tariff to their customers."

This was a shift from previous announcements that energy companies would tell customers about the best tariff available for them.

So what is going on?

Is the best deal the cheapest deal?

Why don't energy companies just offer the cheapest deal anyway?

Confusing stuff isn't it? Why has the subject come up now?

What is the energy regulator's role in all this?

So I'm still going to have to shop around after all?