Just a few short years ago, fracking – the underground extraction of gas from rock – was to revolutionise Britain’s energy production as it has transformed it in the US. Under David Cameron and George Osborne, it was to produce the fuel that would build a bridge from the high-carbon past to the no-carbon future. Just 18 months after the two leading politicians of their generation quit the scene, fracking’s prospects are uncertain. Now companies are preparing for a make-or-break year. On Tuesday Cuadrilla won permission from West Sussex county council to test for oil at its site in Balcombe, where five years ago hundreds of local protesters saw off the company’s efforts to explore its potential. Cuadrilla may read this as a positive message, and insists it is not interested in fracking. But well-organised objectors do not believe the company, and it may be wise not count its chickens just yet.

Another of the big four frackers, Ineos, has also aroused antagonism after a freedom of information request revealed at the weekend that while it had denied in public that it wanted to prospect for gas beneath the scientifically sensitive parts of Sherwood Forest, it has in fact now acquired permission to do just that. It has also announced a legal challenge to Scotland’s fracking ban. Meanwhile, the Department for Business, Energy and Industrial Strategy is imminently expected to approve fracking by the oil and gas company Third Energy at a site in North Yorkshire. It would be the first well to be fracked in the UK since 2011. It would also be a leap of faith. After the activism of the Cameron-Osborne years, Theresa May has shown no interest. She abolished the climate change department, and sounds more concerned about cheaper energy than cleaner energy; last October’s Clean Growth strategy failed to mention fracking at all. Yet Britain is committed to huge cuts in carbon emissions by 2030 – a 57% reduction on 1990 levels. The role for shale gas needs explaining. There is a chance that what might have been a useful stopgap on the road to zero-carbon energy is running out of road to secure a return on the large investments already made.

With each passing month, the advantage of leaving gas in the ground along with coal and oil gains traction. In these columns in December Mrs May stressed her commitment to tackling climate change. On Thursday she will make her first big speech on the environment. Voters care about green policy. She must come clean on fracking.