In these long, lazy days of summer it may have escaped attention that Britain's energy policy could be fundamentally changed.

The prime minister's decision to put the gigantic Hinkley nuclear power station on hold has enormous implications. Bogged down by controversy and massive cost over-runs, there must be considerable doubt it will ever be built. This leaves a vast gap in our energy supply over the next decades. If we are to avoid the lights going out, what options do we have?