The first discovery of oil in the UK waters of the North Sea was in 1969. Revenue from North Sea oil and gas flourished in the 1980s under Prime Minister Margaret Thatcher – when large-scale privatisation in oil took place. During most of the 1980s, the United Kingdom was a net exporter of oil and gas. By the mid-1980s, oil and gas extraction were responsible for 6% of the United Kingdom's economic output. However, this appreciated the value of the British pound which made it difficult for the manufacturing sector to compete – this resulted in the loss of hundreds of thousands of jobs. Since many of the North Sea oilfields were off the coast of Scotland, North Sea oil has been an issue surrounding Scottish independence for decades.