"This is the picture of a vibrant, proactive industry that will continue to make an enormous contribution to UK plc for many years to come," he told the Financial Times.

But in spite of the minister's optimistic assessment, Britain is fast running out of the large reserves of oil and gas that made it one of the leading producers over the past three decades. The decline will have far-reaching consequences - for the country's finances, its balance of payments, its energy and foreign policies.

More broadly, it is part of the general decline of oil sources from beyond the Organisation of Petroleum Exporting Countries that has checked the power of the oil cartel since the oil crises of the 1970s.

BP first struck oil in Britain 35 years ago, when it discovered the massive Forties field off the coast of Scotland. The field was the largest ever discovered in the UK and became a symbol of the oil surge. At its peak, it produced 500,000 barrels a day. Since then it has declined to about one-tenth of that amount.

People have fretted for decades about the day when North Sea oil would run out, but technological advances and new discoveries kept pushing that date into the future. However, production of both oil and gas is now firmly in decline.