Energy bills have more than doubled

A typical dual fuel gas and electricity bill was £610 a year in 2004.

That figure has now risen to £1,320 -- and more than £1,400 for many after the latest round of price increases, including Scottish Power today.

Of that the so-called green levies account for about £112.

So bills have doubled in less than a decade, even if you lop off the green levies.

The £112 is set to rise to £194 in 2020.

It includes £47 from the ECO -- the obligation on suppliers to insulate some people's homes and renew their boilers -- and £11 from the Warm Home Discount, a scheme to reduce bills for low income customers.

See this from DECC on page 78 for the breakdown of the green charges which David Cameron says he is going to roll back.