The impact on the water supply will inevitably remain a matter for concern, because of the tiny amounts of chemicals dissolved in water injected to fracture the source rock. The techniques themselves are constantly being refined and, compared to the early days in the US, the chemicals used now appear innocuous. Hydraulic fracturing does, according to the US Geological Survey, cause small but harmless earthquakes, although the recycling of waste water into deep wells can cause perceptibly larger quakes. It should be noted that most subterranean activities, such as coal mining, can cause subsidence or earthquakes. 

There are several shale gas exploration sites around Britain but the most significant is Cuadrilla Resources' initiative on the Fylde coast of Lancashire. Cuadrilla is backed by Lord Browne, lately the boss of BP. Last September Cuadrilla announced that it had identified reserves in place of 200 trillion cubic feet — roughly 20 times the proven reserves of conventional natural gas in the North Sea. Even assuming only a 10 per cent recovery rate — very conservative by North American standards — this one find potentially trebles Britain's gas reserves, and provides George Osborne and his successors at the Treasury with an enormous opportunity.

The reaction to this good news has been, at best, muted. The BBC, inevitably, reported the story as an environmental disaster in the making. The Financial Times, preoccupied with rescuing the euro, paid it scant attention. Ofgem, which in recent years has dwindled from an effective regulator of competition to an alternative delivery vehicle for government green energy policies, reissued an old report by some tame consultants insisting that shale gas held little promise for the UK. The formal reaction from a Department of Energy and Climate Change (DECC) spokesman was discouraging: "Any development must sit with our plans for a strong portfolio of energy sources as we move to a low carbon economy, including renewables, nuclear and clean coal and gas." This unenthusiastic line was repeated by the hapless Chris Huhne during his last months as Secretary of State at DECC, notably in a Guardian interview in which he repeated the demonstrable nonsense that shale drilling could lead to gas flames spurting from domestic water taps.

So, how much might this unwanted and embarrassing Fylde gas discovery be worth to the British economy? Cuadrilla is planning to bring the field up to full production by about 2020. Privately they believe they will be producing 1 trillion cubic feet, or 28 billion cubic metres a year. That is about half of current UK gas production from the declining North Sea fields.

At today's prices that amount of Fylde gas would be worth about £4.2 billion a year to the Exchequer early in the next decade. It would also improve the balance of payments by £7 billion, and go a long way to restoring Britain's energy independence. Tens of thousands of real jobs would be created in a depressed English region. What's not to like?