Celebrities gathered in Bristol on Friday for a sneak preview of Banksy's homecoming exhibition, as organisers prepared for "enormous queues" when the doors open to the public on Saturday.

Featuring 100 pieces, the exhibition has taken over Bristol's City Museum and Art Gallery, and sent a ripple of excitement through the international art world.

Among the famous faces at last night's launch party were Stone Roses singer Ian Brown, actor Sean Pertwee and pop star Ms Dynamite.

The show, entitled Banksy versus Bristol Museum, was installed over two days in an audacious secret move that most of the museum's own staff did not even know about.

TV presenter Carol Vorderman, comedian Dom Jolly, chef Hugh Fernley-Whittingstall and cult Bristol band Massive Attack were also at the party.

Bristol funnyman Justin Lee Collins said: "I'm very excited about this whole thing. It's great for Bristol."

Glastonbury Festival founder Michael Eavis, who strode through the event in his usual festival garb of a pair of shorts and a sweater, said he was thrilled to see so much Banksy work in one place.

"Banksy comes to Glastonbury every year, so he's a real friend of the festival. It's great to see the old portaloos again," he said.

"Out of all the new pieces, I'm particularly impressed by the wall of graffiti that's lying on its side in one of the galleries. It's incredibly well done."

Former Gloucestershire and England fast-bowler Syd Lawrence, said he was amazed at the scale of the exhibition.

"It's incredible," he said. "I've known Banksy for years, from spending time with the Massive Attack boys in the 1990s. It's brilliant to see the way his art has developed over the years.

"The pieces are so powerful. There is one painting here with a Ku Klux Klan member hanging from a tree. He's able to make such a moving statement so simply."

Veteran civil rights campaigner Paul Stephenson was also impressed with the exhibition.

He said: "I think that every museum director in the country will be touched by what is clearly a social revolution in the perception of museums.

"Museums can never be the same after what has happened here in Bristol. This clearly has become the people's museum."

Twenty-four hour security has been increased at the venue to protect the works, which cumulatively are worth millions of pounds.

The exhibition, which runs until the end of August, is expected to bring hundreds of thousands of people into the city. The last comparable Banksy show, in Los Angeles in 2006, attracted 75,000 people in three days.

Banksy's spokeman, Jo Brooks, said: "We're expecting enormous queues tomorrow, with people probably camping out all night to keep their space. But we are here for almost three months, so you don't need to panic."

Councillor Simon Cook, deputy leader of the city council, who is also in charge of sports, culture, tourism and capital projects, said: "This show will give Bristol's economy a huge boost. Banksy has a tremendous international appeal, and we can expect to see hundreds of thousands of people coming to Bristol to see the show.

"That means hotel rooms will fill up across the city, restaurants will find themselves busy throughout the summer, and visitors will spend time exploring Bristol while they're here – visiting our other attractions and buying things in our shops."

After getting a sneak preview of the show yesterday morning, he said that fans will not be disappointed.

"It's provocative," he said. "Much of it will be controversial, and it won't be to everyone's tastes. But that's a big part of the role of art. It is meant to shock. For as long as our art galleries are exhibiting works that shock, we're doing something right.

"My particular favourite piece in the show is the CCTV camera feeding its nesting young. It's such a simple but powerful statement about the way our surveillance society develops – with CCTV cameras breeding more CCTV cameras."

In a statement, Banksy said: "Maybe one day graffiti art will hang in lots of museums and be viewed in the same way as other modern art, although personally I hope it never sinks that low."

City council director of museums and galleries Kate Brindley led the organisation of the Banksy exhibition, a secret operation that has taken her 10 months.

In all that time only a handful of staff knew about it – and she even managed to keep it secret from her own partner.

"It is just a once-in-a-generation opportunity," she said. "Banksy and his people approached us and said would we be involved in a major show.

"I think it really meant a lot to him. We had to talk it all through with him, and he had lots of ideas, knew the building well and has been here a lot.

"I just knew that when we were approached we couldn't pass up the opportunity.

"It is just a gift for Bristol, and I wouldn't have been doing my job properly if I hadn't taken the offer up."

For the next three months the museum's reception will be in the ice cream van installation, in the middle of the ground floor foyer.

A team of eight staff will have the distinct honour of answering phones and carrying out their duties from inside a rather cramped Banksy artwork.

Helen Edwards, front of house manager, said: "It is fine in there. It has a fan, so is probably the coolest place in the building, in both senses of the word.

"There will only be one person in there at a time and we have a team of eight who rotate through reception duties, so they will all get to work in there.

"Unfortunately we won't be serving ice creams, but I would absolutely love to."

Staff at the museum need to cope with the expected surge in visitors.

Rebecca Burton, deputy head of Bristol Museums' archive and collections, said: "We can only get around 600-700 people in the building at a time. Once you're in, we're not going to rush you out. So it will be a case of one-in, one-out.

"That's going to mean some very long queues, especially in the first few weeks.

"I'm very aware that Banksy's biggest fans are going to want to spend hours in here looking at every nuance of every piece. So the flow of visitors may be quite slow."

The economic benefits of the exhibition could prove to be enormous for the city.

Mark Passmore, manager of the Avon Gorge Hotel, said: "The museum is in walking distance from the hotel so it has the potential to boost our trade over the next three months."

Sophie Stevens, of the Full Moon Hotel in Stokes Croft says she expects the 70 rooms in the backpacker hostel to fill up quickly.

"We tend to attract the artistic community because we're at the heart of Stoke's Croft – just down the road from Banksy's famous Mild, Mild West mural," she said.

James Durie, deputy chief executive of Business West, the chamber of commerce for Bristol, said: "This could have a very significant effect for the city's economy."