More people visited museums and galleries than attended all of league football including the Premiership last year, according to a report by the respected analyst Tony Travers.
He estimated the annual economic benefit of the UK's major museums and galleries at £1.5bn with roughly £1 in every £1,000 in the UK economy directly related to the sector.
But Mr Travers, of the London School of Economics, warned that theinstitutions would need extra money if they were going to continue to deliver and not fall behind heavily funded international competitors.
Income has not been rising as fast as staff and other inflationary costs and up to a third of museum displays and facilities are in need of significant renovation.
The report, Museums and Galleries in Britain: Economic, Social and Creative Impacts, was commissioned by the National Museum Directors' Conference and the Museums, Libraries and Archives Council in the run- up to the next Comprehensive Spending Review where cuts are threatened.
Its message on the significance of museums and galleries to the British economy as well as to the national well-being will be stressed in negotiations.
Mr Travers described Britain's museums and galleries as among the very best in the world. With greater capacity to expand and improve, they could help Britain be a world leader in creativity and scholarship.
"The agglomeration of institutions, talent and audiences in Britain has parallels in only a few other countries," he said. "Britain's museums and galleries underpin the creativity upon which future high value-added economic activity is likely to be based. However, there is a risk they will be taken for granted and not seen as the potential opportunity they represent. The only question is whether there is a national desire to deliver, maintain and expand this particularly creative sector."
Mark Jones, director of the Victoria and Albert Museum and chairman of the directors' conference, said museums and galleries were one of the Government's great successes. "I hope this will not be rewarded with cuts to core funding. As the report shows, we can't continue to deliver to these exceptional standards and to maintain the UK's position as world leaders without adequate funding."
There are 1,848 museums in the UK. Central or local government grants account for more than half of their income although they generate as much as £200m. But capital expenditure has dropped sharply in the past five years with the availability of resources apparently unrelated to the sector's needs, Mr Travers said.
He also warned that there was a problem with the free admission policy to the national collections. "There are some who argue for free admissions as an absolute right. The difficulty with this position is that it appears to condemn museums and galleries to a flow of public resources that is likely to decline in real terms."Reuse content