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North Sea oil and gas has made a huge contribution to the British economy over the last three decades but that contribution cannot be encapsulated as a single value in 2007 (or any other) prices. Between 1997 and 2006, the cumulative gross revenue of the UK upstream oil and gas sector, principally from sales of oil and gas produced from the North Sea, amounted to £761 billion in 2006 prices. Over the same period, cumulative operating costs of the sector amounted to £129 billion in 2006 prices. The cumulative total gross operating surplus of the UK upstream oil and gas sector between 1997 and 2006 was thus £632 billion in 2006 prices. The gross operating surplus of the sector is a little less than its gross value added (GVA), data for which go back only to 1985. GVA is the best single measure of a sector's contribution to Gross Domestic Product. Over the period 1997 to 2006, the UK upstream oil and gas sector spent a further £44 billion in 2006 prices on exploration and appraisal and £171 billion on capital expenditure (these and previous data come from the BERR Oil and Gas website—http://www.og.dti.gov.uk/information/bb_updates/appendices/Appendix7.htm). It also contributed £233 billion in 2006/07 prices to the Exchequer over the period 1977/78 to 2006/07 (source: BERR Oil and Gas website—http://www.og.dti.gov.uk/information/bb_updates/appendices/Appendix8.htm). None of these figures captures the overall net impact the sector has had on the economy.