There could be up to 100 billion barrels of oil onshore beneath southern England, the chief executive of a small exploration firm told the BBC in an interview on Thursday. To which the correct response is “yes, but”. Based on an analysis of samples from a single well drilled near London’s Gatwick airport, UK Oil and Gas Investments estimates there could be 158 million barrels per square mile in the local area. Horse Hill, where the well was drilled, is part of the Weald Basin, which stretches across large parts of the counties of Dorset, Hampshire, West and East Sussex, and Surrey, as well as parts of neighboring Wiltshire and Kent. Scaled up across the whole of the basin, there could be 50-100 billion barrels of oil, though only 3-15 percent might be technically recoverable, the firm admitted (“Oil discovery near Gatwick airport significant” April 9). […]