The era of cheap energy is over and will never return as Britain pays the price of turning into a low-carbon economy, the former chairman of the Environment Agency has warned. Sir John Harman accuses politicians of failing to be honest with people about the costs of developing and delivering new forms of clean energy.

And he calls for measures to combat fuel poverty, through price controls, subsidies or higher state benefits to prevent the creation of a new class of low-carbon poor.

In a hard-hitting Fabian Society pamphlet to be published this month, Sir John accuses politicians of failing to match their rhetoric on green issues with action, saying they are "badly out of touch with the reality". In The Green Crunch, he writes: "It is extremely unlikely that we will ever get back to the retail energy prices of the past 15 years or so. Yet I do not think that this fact is being squarely presented to the electorate nor would it be an obvious vote-winner to do so.

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"We need to acknowledge that there is, in a civilised society, a right to expect affordable access to warmth, light, and the other benefits which energy delivers and that this can only be protected as prices rise by intervention, either in the energy markets or through the welfare system."

He points to Gordon Brown's reluctance to bring in the green taxes he promised as Chancellor in 1997. But he argues that Labour can learn lessons from Barack Obama's victory in a "gas-addicted" United States and is the natural party to meet the environmental challenge.

Sir John, a former Labour council leader who chaired the Environment Agency for eight years until last summer, urges politicians to be more honest with people about the threat from climate change, saying that the environment should be regarded as just as important as economic and social issues. His call comes as green groups fear the environment is falling down the politicians' list of priorities because of the recession.