Is nationalisation the vote-winner which Keir Starmer believes it to be? We will find out in due course, but my hunch is that the British public as a whole care a lot less about who owns the train carriages they ride in and the power stations which generate their electricity than Labour MPs do.

What they care about rather more, surely, is whether their trains arrive on time and whether their lights stay on. No one who remembers British Rail will be under any illusions that public ownership is a panacea for a functioning railway, and neither will anyone who remembers the three-day week be fooled into thinking a public-owned power industry guarantees keeping the lights on.

So what to make of Labour’s plan for Great British Energy – a public-owned company which would invest in wind, solar and possibly tidal energy? There is no reason that a public-owned company cannot operate wind farms, but there is no reason, either, to suppose that Keir Starmer has even addressed, still less solved, the fundamental problem of trying to operate a national grid based on intermittent wind and solar energy. The renewable industry has already proven that it is very efficient at providing affordable power when offered guaranteed, index-linked prices for 15 years into the future.

What the market has not been so forthcoming with, on the other hand, is energy storage to cope with the many occasions when wind and solar cannot deliver the goods. There is a very good reason for this. All known forms of energy storage – whether it be battery, pumped storage, hydrogen or any else – are extremely expensive, costing several times as much as generating the energy in the first place. Starmer’s plan for Great British Energy does not appear to offer anything towards solving this problem.

Until it is solved, the idea of a grid based on wind and solar energy, without back-up from gas, remains pie in the sky – and the government’s plan to phase out gas power stations from 2035 will condemn us to extremely expensive electricity from that date, and perhaps to frequent power cuts too. If Starmer has a cunning plan to address that issue, he sadly didn’t share it with us today.