Hundreds of demonstrators have shone torches on to the Sydney Opera House to protest against controversial advertising for a horse race that has divided the city and exposed the fault lines in Australia’s culture wars.

The protesters, who sought to interfere with the display on the world heritage-listed structure, chanted “Not for sale” and “Whose house? Our house”.

Racing New South Wales, the body behind the promotion, had envisioned Tuesday’s light show as the grand launch of the $13m Everest horse race. Instead, it has faced an intense backlash.

By Tuesday more than a quarter of a million people had signed a petition against the plan, sparked by concern about the commercialisation of the landmark building and the influence of the city’s vocal conservative media.

A sizeable police presence patrolled the shores of Sydney harbour on Tuesday evening, while riot officers cordoned off some areas closer to the water. The protest, however, was mostly good-spirited. When the sails finally lit up at about 7.40pm the crowd erupted in a chorus of boos, chanting “Not a fucking billboard”, “Boring” and “The graphics are shit”.

Facebook Twitter Pinterest Demonstrators in Sydney protest against the decision to project the barrier draw results for Racing NSW’s multimillion dollar race on to the sails of the Opera House. Photograph: Paul Braven/AP

The Opera House saga is an example of what Australians like to call a very Sydney story: populated with gambling industry figures and a conservative media host seemingly calling the shots in the city’s politics.

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The decision to promote the horse race had originally been opposed by the Opera House’s chief executive, Louise Herron. Racing NSW had applied to the Opera House to use it as a venue to promote the race, but Herron drew the line at projecting horses’ names and the name of the race on to the sails.

State legislation requires that the projection of colours and images on to the sails of the Opera House should be “confined to exceptional, non-commercial occasions of brief duration”, and Herron had wanted a more subtle display that didn’t include the race trophy and advertising.

On Friday the state premier, Gladys Berejiklian, overruled Herron and ordered the Opera House to allow the display.

Berejiklian’s intervention came after intense pressure from the Rupert Murdoch-owned Daily Telegraph newspaper and Alan Jones, a conservative shock jock who has the ear of many politicians.

Jones is often labelled a kingmaker in conservative political circles. Aged 77, he is a former Australian rugby union coach and a firebrand presenter who habitually uses his top-rating show to target his political opponents.

In a widely criticised interview on Friday – for which he later apologised – he berated the Opera House boss, refusing to listen to her answers and at one stage exclaiming: “Who the hell do you think you are?”. He also threatened to tell Berejiklian to sack her.

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In a furious statement on Monday, Michael Lynch, the former head of the Opera House, said: “I find it extraordinary that the state politicians on both sides have somehow decided that this is in the interests of Sydney, New South Wales or Australia to corrupt the way the Opera House works, to corrupt the artistic integrity of the building and to be able to use it in any way a politician wants.

“I would not regard myself as precious or elitist and I just find the lily-livered approach by the politicians on this issue [and] the nexus between the gambling bodies and the politicians seriously disturbing.”

The lord mayor of Sydney, Clover Moore, told the Guardian that the promotion was “blatant commercialisation of Australia’s world heritage-listed Opera House for an industry notorious for damaging gambling and animal cruelty”.

Others, including prominent politicians on the Australian right, dismissed those concerns. The prime minister, Scott Morrison, supported the plan, calling the Opera House “the biggest billboard Sydney has”.

“We’re talking about an event that is one of the big money spinners for the state,” he said. “It creates jobs. This isn’t about advertising a packet of chips, this is about advertising one of the biggest events that New South Wales holds. Frankly, I thought it was a bit of a no-brainer, I can’t work out what all the fuss is about.”

Facebook Twitter Pinterest The protest called for the focus to be on ‘sails not sales’. Photograph: James D Morgan/Getty Images

Wendy Aylward, from the Sydney suburb of Arncliffe, told the Guardian she attended Tuesday’s protest to send a message to the government. “We’re all here to show how strongly we feel that the Opera House should not be used in this way,” she said. “I personally think Alan Jones’s influence is overstated, but I’m really concerned about the commercialisation of the building.”

Her friend Jo Fraser, from Enmore, said politicians seemed to have misjudged the opposition to the projection. “I’m not against things like the Wallabies [rugby team] or the rugby league being celebrated [on the sails] but it’s a bit different,” she said. “I think it’s a really slippery slope.”

The projection lasted about 30 minutes and ended to a raucous round of cheers and chants of “We love you Louise”, in reference to Herron.

Before the display, the Green MP for Newtown, Jenny Leong, said the protesters had “drawn a line in the sand” and were standing up to “a shock jock who runs this city”.

“People have said enough to bullies, enough to the idea that people with power can buy this city,” she said.