Shale gas exploration has been progressing at what seems to be a slow pace, but operators say the gradual changes Mr. Cameron has made to Britain’s regulations are giving the country a chance to emerge as an attractive destination for shale investment.

Other European governments have been harder to convince that shale gas is worth the potential political unrest. Many Europeans worry that the hydraulic fracturing technique, known as fracking, that is used in shale production could pollute underground water supplies and lead to other environmental damage.

France has banned fracking, while Germany has in place a de facto moratorium on the practice.

Some East European countries, which want to ease their dependence on Russia, have been more receptive to the shale gas industry. In Poland, for example, more than 50 wells have been drilled. The results have been inconclusive. Some large companies like Exxon Mobil and Italy’s Eni have pulled out, but smaller companies are still trying to work out the right techniques to tap the rocks.

The overall reluctance to exploit shale gas reduces Europe’s energy options — a point highlighted by the confrontation between Russia and Ukraine. With gas production in the European Union declining and Germany phasing out nuclear energy, there seems to be little alternative but a heavy reliance on Russia, which supplies about one-third of the gas consumed in the union.

People in the industry say that the response to Britain’s new round of licensing will be an important indicator of whether the government’s policies are succeeding. So far, the British shale industry has been the province of a few small companies, limiting the capital that could be applied to drilling programs. Those limitations seem to be easing: Total of France made a shale gas investment in Britain this year; Centrica, a British utility, and GDF Suez, a French energy company, both announced similar moves last year.