Sir – The controversy over nuclear power rumbles on. To what extent, in practice, we could keep our industry, lighting, and domestic equipment running without energy from nuclear and fossil fuel is ultimately a matter of arithmetic.

The arithmetic has now been done for us by David JC MacKay, who is professor of natural philosophy in the Department of Physics, University of Cambridge. Anyone uncertain of the realities that must underlie national fuel policy can obtain a free download of his book Sustainable Energy — without the hot air at www.withouthotair.com Essential reading.

John Grimley Evans Oxford