We always knew that Banksy's summer show had been good for Bristol.

When the exhibition closed at the end of August, there were guesses that the city's economy had benefited to the tune of £10 million.

Today, the Evening Post reveals the real figure was an extraordinary £15 million.

This will come as no surprise to those who saw some of the 308,000 visitors who queued for hours to see the street artist's work, or the owners of the packed bars and shops around Bristol City Museum and Art Gallery, or the hoteliers whose room reservations were boosted by a staggering 55,000 Banksy bookings.

In fact, those bars and hotels saw their incomes rise by more than £6 million, and almost 6,500 visitors came to the exhibition from overseas.

City tourism experts tell us today that no other event has come close to providing that kind of revenue.

Credit, too, should go to Bristol City Council. Not just for having the nerve to host such a potentially controversial and subversive show, but for having the courage to let the artist take over the museum.

Perhaps inevitably, Bansky still has detractors in the city who cannot separate the "street vandal" from the acclaimed artist. Their arguments against him are usually based on the bad example he sets or what he has cost the council in the past. The sad truth, however, is there are some Bristolians who will never be happy or give credit where it's due.

Meanwhile, Banksy probably doesn't even care. He doesn't want to be part of the city's establishment. He is certainly no capitalist and he may well even be uncomfortable with what he has done for the city's economy.

But Banksy's extraordinary achievement means Bristol should always be grateful to its prodigal son.