The Norwich Sound and Vision team at Norwich Arts Centre(l to r) Rosie Arnold, Jenny Allison and Adrian Cooke. PHOTO BY SIMON FINLAY

Norwich Sound and Vision (NSV) welcomed 7,010 people last October, an increase from 4,800 in 2011, with around 25pc from outside the city.

Adrian Cooke, NSV festival director, said it was not possible to account for every penny spent in the city because of NSV but the research placed the figure at £315,580 over three days. He said this included hotels and restaurants but not ticket sales.

Mr Cooke added: “The figure is based on a formula based on what people do, their behaviour and whether they are here for the night or day. That’s a conservative estimate but it’s certainly at least that. I knew the restaurants were full as I couldn’t get a table.”

NSV returns for its fourth year from October 10-12. Norwich Arts Centre acted as the NSV hub in 2012, with 11 other venues used.

NSV’s surveys found 13pc of visitors were from outside the east of England and of the people from Norwich, four out of 10 said they had never visited the arts centre before.

Mr Cooke said: “We’ve got lots of anecdotal quotes from people, which is really cool, but when you come to writing that bid for funding, you need it in black and white and it also affects your planning. This year will be bigger with more variety.”

Before the 2012 event, the Norfolk Chamber of Commerce labelled NSV a “fantastic showcase” for the city.