Work of the man who defied repression of Beijing goes on sale in London for £2m

Execution is a reminder of another China. The regime may want the world to see Shanghai's skyscrapers and the bird's-nest stadium that will host next year's Olympics, but the artist Yue Minjun depicts a Tiananmen Square of bloodshed and hopes of liberty lost.

It is a chilling painting whose brief history has been entwined with the life of its artist and the autocratic state that produced it. Few people have laid eyes on it. Many of those who have, did so in secret. Next week though, Execution is to be displayed in public for the first time, when it is to be auctioned at Sotheby's in London.

The work is estimated to sell for up to £2m, partly because of its provenance, but also because Minjun is China's most celebrated contemporary artist. In June, another of his paintings, The Pope, sold for £2.1m, becoming the most expensive artwork by a Chinese contemporary artist at auction and exceeding the value of an Andy Warhol in the same sale.

Latterly, the Chinese government has embraced Minjun as a leading nationalist figure, and last month offered him his own museum in Sichuan province, in western China. But in 1996, it was a different matter.

Then, a young British art collector was led to a darkened room of a Hong Kong gallery by a nervous dealer to seal a secret deal for Execution – then an artwork so politically incendiary that, if publicly displayed, it could endanger the life of the subversive artist who had defied the regime to paint it. The purchaser then, who wishes to remain anonymous, said that buying Execution was a highly nerve-racking experience.

Manfred Schoeni, the owner of the gallery in Hong Kong, was reluctant to sell it for fear of the political repercussions it might cause. He only agreed to part with it on the strict understanding that it would not be shown publicly for at least five years.

Even after the deal had been struck and money had changed hands, Mr Schoeni only allowed the painting to leave the premises on the condition that it was shipped out of the country and to the UK.

Minjun, who was living on the bohemian margins of society at the time and had already attracted the disapproval of local police, became one of the most prominent figures of the Chinese avant-garde movement of the 1990s. Despite state censure, he sold his paintings in secrecy during the repressive decade following the Tiananmen massacre of 1989. Execution was first sold for around £10,000.

The current owner said: "This gallery was away from the row of other galleries in Hong Kong and I knew the owner. He said one day, 'I've got something to show you' and pulled out the painting. It was not for sale but I was so struck by it, I knew I had to buy it, whatever it took. But I also knew it would be explosive.

"Manfred said it made him nervous. He was going around villages in China looking for this stuff and then buying it. But it was politically dangerous. Even after I'd bought it, he wouldn't let me take it but had it shipped directly from the gallery to London."

Alex Branczik, a contemporary art specialist at Sotheby's, said it was evident that Execution was painted as a response to Tiananmen. "Like the photograph of the 'Unknown Rebel' halting the advance of a column of tanks on to the square, Execution distils the sentiment of protest. After Tiananmen, artists were already persecuted by the state, but this was Minjun's response to Tiananmen. If viewed publicly in China or Hong Kong, it would have incriminated him," he said.

He added that, although unseen by the public, it is regarded as one of the most historically significant paintings of the Chinese avant-garde to appear at auction. Set against the vermillion walls of Tiananmen Square, it captures the "shattered idealism of a generation that followed in the wake of the political turmoil of 1989".

But what was construed as more radical at the time was Minjun's explicit references in the painting to Goya's The Execution of the Defenders of Madrid, painted in 1814, and Manet's 1868 work, The Execution of Maximilian. Both have politically incendiary messages – for Goya the celebration of the victory of Spanish revolutionaries over the invading Napoleonic armies, and for Manet expressing dissent against Napoleon III's foreign policy in Mexico, where the French ruler deserted his former ally, Emperor Maximilian, and condemned him to certain death at the hands of insurgents.

At a time when the Chinese government had banned any cultural references to the West, Minjun placed himself in danger by connecting China to canonical figures of Western art history.