It may never be possible to account for the full cultural impact that the Banksy exhibition has had on the city – will it reinvigorate the artistic community? Will it become a catalyst to inspire the next generation of Banksys?

The truth is, nobody really knows. These are the sorts of questions that might only be answered retrospectively – 20 or 30 years down the line.

While we can speculate about what the show has given the city in cultural terms, the economic impact – the cold hard cash it's brought into Bristol over the summer – is a little easier to sum up. The first figure to be bandied around by the experts, is that £10 million may have been injected into the local economy at the height of the recession – just when it's most needed.

"When you look at the inscription on the outside of the museum, it says that the building was a gift from Sir William Henry Wills, and more than 100 years on, the last 12 weeks have been a tremendous gift to the city from Banksy," says Ned Cussen, partner at commercial consultants King Sturge, which is based only a few hundred yards from the museum.

"As a local business, we were invited by the city council to carry out an economic analysis of the Banksy Effect. There will be a full statistical report released later in the year, but we've already learnt a lot anecdotally – simply by talking to people in businesses across the city. The fascinating thing is that despite the fact that we've been in the middle of a major recession over the summer, there is an economic microclimate in the roads immediately surrounding the museum. All around Park Street, Park Row and Queen's Road the businesses have actually seen a mini- boom, all thanks to Banksy.

"You would absolutely expect the local bars and restaurants to do well out of it, but it's interesting to see how it's had a real knock-on effect for all businesses locally.

"For example, fashion outlets in the neighbouring streets – primarily Park Street and Queen's Road – have seen an average rise in sales of 30 per cent. So people have been staying in the area long enough to buy clothes while they're here. There are also reports that one nearby charity shop doubled its turnover for the period, simply through the sale of Banksy memorabilia. Even in terms of car parking, the local car parks in the West End have seen a massive boost – I know I've had to park two floors higher than I normally would throughout the summer. Car parking income is up by £100,000 from 2008/9 figures.

"There's no doubt it's been brilliant for this part of the city. We're yet to see how that effect has fanned out to businesses further afield – but it's bound to have created a ripple across the city centre, in places like Broadmead and Cabot Circus."

It's unsurprising, given that the exhibition has attracted more than 300,000 visitors over the course of 12 weeks – many from outside the city.

Those joining the now famous queue have included people who have made special journeys to see the show from as far afield as Australia, Uruguay and Japan.

Yvonne Colgan, of the Bristol Hospitality Forum, says hotels across the city have seen a major boost.

"Hoteliers have seen their rooms getting filled up, even in the normally quiet mid-week slots," she says.

The rich mix of people attracted to join the Banksy queue – of all ages, and from all walks of life – has meant the influx of visitors has had a positive effect on all types of accommodation – from backpacker guesthouses to Bristol's top hotels.

"It's been a boom across the board for hotels, B&Bs and guesthouses," Yvonne says.

"We've even seen that tickets sales on the Bristol International airport bus to the museum stop in Queen's Road have more than doubled, which is a pretty good indication that people have been getting off aeroplanes on a real mission to see Banksy.

"Often foreign visitors to the UK come to see London, but rarely get any further west than Bath. But this show has really encouraged people to come out and see Bristol."

There are also indications that the Banksy Effect has had a positive knock-on for other tourist attractions – with people paying a visit to places like Bristol Zoo and the ss Great Britain while they have been here.

Dr Jo Gipps, director of Bristol Zoo Gardens, says the zoo has been busy all summer.

"The Banksy exhibition has shone the spotlight on Bristol as a fantastic city and tourist destination, and everything it has to offer," she says.

"Given the current economic conditions, it has been great to hear how many tourists from outside Bristol have come to see the show, and have visited other great local attractions while they've been here."

Susannah Cole, the ss Great Britain Trust's director of development, says: "There is no doubt that the Banksy exhibition has attracted great numbers to Bristol from across the UK and beyond. Brunel's ss Great Britain has also seen visitor numbers exceeding forecasts for August by more than 22 per cent.

"We believe there are a number of factors influencing these increases. Certainly Banksy and the Banksy queue – where people have been put off by the wait and are looking for alternative entertainment – has benefited the ss Great Britain."

Councillor Simon Cook, deputy leader of the city council and cabinet member for culture, sport and capital projects, says the expense of the show has been a good investment.

Although Banksy only received a nominal £1 for staging the event, it's cost thousands to employ an extra 32 members of staff throughout the summer.

"We have put a considerable amount of money into managing the exhibition, but when you hear about figures of £10 million coming into the local economy as a result of it, you have to say it's got to be well worth every penny.

"I think the Banksy exhibition has lifted the city up a stage in terms of our national standing in artistic matters. But we're still a long way behind big cities like Birmingham, Manchester, Liverpool and London.

"I hope people will realise that we do need to increase the amount we spend on art and culture in the city if we're to compete with other cities. This exhibition demonstrates what a boost cultural events can give the city's economy as a whole.

"You only have to look at the fact that the donations boxes have received £45,000 over the 12 weeks – that is money that will go directly into the coffers of the museum. Hopefully that will allow us to purchase something for the museum's permanent collection."

Ned Cussen, of King Sturge, says the exhibition has changed the cultural landscape of the city permanently.

"There will be a lasting effect," says Ned. "That will manifest itself in terms of civic pride and raised profile as a tourist destination. I certainly think Bristol has a lot for which to thank Banksy. He's an old Bristol boy, who has done his city proud."