This morning’s papers report that there may be yet another Government u-turn, this time on green policy. According to The Sun, ministers are preparing to give families more time to switch from ‘dirty’ gas boilers to greener alternatives.

British homes apparently make up a substantial chunk of this country’s emissions, and changing that has therefore to be front and centre of the Government’s plans to achieve ‘Net Zero’.

However, overhauling millions of houses will be eye-wateringly expensive. And unlike a big set-piece project such as a new power station or similar, it will cause disruption for many millions of voters.

Worst, it will impose costs too. The impact of simply legislating to ban gas boilers, which was the Government’s plan, is to impose the financial burden of replacing them on ordinary households. Some in Whitehall were pushing for ‘carbon cheques’ to help offset such costs – but these have been vetoed by the Treasury. Instead, the boiler ban may get pushed back by up to 15 years.

Is this an example of the lamented ‘Treasury brain’, which has often seen the UK’s long-term policy priorities subordinated to Exchequer shibboleths? Or does this row simply highlight the shortcomings of the ‘legally-binding targets’ approach to policymaking?

I have written before about how it increases the democratic process’s exposure to judicial meddling. But it is also a problem of trying to impose rigid plans on an unknowable future. Large amounts of green spending must have seemed much more practical before the Treasury’s extraordinary interventions to support the economy through the Covid-19 pandemic.

Then there’s new technology. No doubt Net Zero will help to drive R&D investment in clean tech, and this will be extremely welcome. But even if so, the exact nature and timescale of technological change is very hard to predict.

To take just one example, one reason New Labour reject the UK Ultraspeed maglev alternative to HS2 was expert advice to the effect that its green benefits would be offset by the coal burned to generate the energy it needed and the pollution caused by passengers driving to out-of-town stations. Yet we have already all but banished coal from British energy generation, and by the time even HS2 is finished the Government plans to be well on the way to the electric car revolution!

It seems an unenviable dilemma. The more politicians put off interventions towards Net Zero, the more brutal the scramble to hit it as the deadline approaches. But the earlier they move, the greater the chances of a policy being overtaken by events or technological change.

One can see why politicians with an eye on today’s electorate might be tempted to start putting off expensive decisions. But if the Government wants to hit Net Zero, it is going to have to foot the bill.