At the heart of the Government’s Heat and Buildings Strategy is a calculation: that enough new homes will be built; that heat pumps will come down in price sufficiently and that the Treasury will provide enough subsidies for its ambitions to be realised.

A further assumption must be that present homes can be adapted successfully, that the pumps will work sufficiently well and their installation prove sufficiently undisruptive, that there will be enough electricity all round, and that the exercise is essential in the first place.

This site supports decarbonisation – and notes that the world is gradually going green.  But we don’t believe that much of the above will happen and that the Government will deliver all its targets: in particular, that of the installation of 600,000 heat pumps by 2028.

Even if the new homes arrive and the costs come down as planned, we doubt whether voters will tolerate the disruption, whether installation will work well for present homes – and whether enough of them will be insulated.

In particular, Rishi Sunak has no enthusiasm for Net Zero, and doubtless grasps the logic previously set out on this site by Bim Afolami: that the demand for subsidies will not be confined to those enduring fuel poverty.

No Government has ever wanted a global summit over which it will preside to fail, and the Strategy must be seen in the context of COP26, which will shortly open.

The politics of the summit made it essential for Ministers to get an ambitious strategy out before it opens, and Number Ten and the Treasury have duly come to an accommodation.

But the proof of the Government’s green pudding will be in the eating and, regardless of the success or failure of COP26 more widely, we suspect that, come 2028, it will miss its heat pumps target while proclaiming that real progress has been made towards it.

And Britain will continue to reduce its emissions, though more slowly than Ministers had hoped.  For all our sakes, they should be keeping their eye on the main prize.

Namely, how best to square reducing emissions, prices that consumers can afford and security of supply so that the lights stay on.  In a country with a complex planning system, litigation-conscious local campaigners, and pressure on space.

Plus a strong Treasury that is institutionally suspicious of grand projets.  Put all that together, and one understands why recent governments have made a dash for gas from abroad.

Or that although Britain established the world’s first civil nuclear programme, the industry’s contribution to the nation’s electricity has been in decline since 1997.

Or that jittery Conservative backbenchers have scared the Government off fracking.  In that triangle of aims, successive administrations have overlooked security of supply.  On which they should now focus.