It is commonplace to say that fusion is always 50 years away. Janet Wood looked behind the cliché and found at least one company that wants to have its first commercial-scale plant ready to go in five years. Will any of it look familiar to investors?

Fusion researchers are always keen to talk through the reaction. That’s not surprising: it requires them to create a plasma and compress it so much, at temperatures in the thousands of degrees, that the same fusion process takes place as happens in the sun.

But I take it as read that it will work eventually.