The student audience was handpicked, the questions were choreographed and a deal was arranged with the media to ensure favourable coverage: welcome to the Barack Obama town hall meeting, Shanghai-style.

A desire by the Chinese to micromanage the event threatened to scupper it altogether, and it went ahead only after a last-minute agreement over live broadcasting arrangements. In the end it was President Obama, the only element the authorities couldn’t control, who strayed decidedly off script by calling for China to allow its vast internet audience uncensored access to the web, and talking about citizens’ basic rights and freedom of speech.

The question-and-answer session was shown live only on Shanghai television but the text was allowed to run in full later on the state-run Xinhua news agency.

It appeared that only the party faithful were allowed to raise their hands, since most questions came from members of the Communist Youth League. However, one of the thousands that had been posted online was put by the US Ambassador, Jon Huntsman. Did Mr Obama know, he asked, about the “Great Firewall of China” — the blocks that China’s censors impose on internet traffic to separate the country’s 350 million web users from content deemed inappropriate?

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Mr Obama seized his chance. “I have always been a strong supporter of open internet use. I am a big supporter of non-censorship,” he said, adding that a free flow of information was a source of strength.

As he was speaking, authorities in Beijing, where Mr Obama arrived late yesterday, were clamping down on dissidents. Among the dozens detained was Qi Zhiyong, who lost a leg at Tiananamen Square in 1989.

The forum marked Mr Obama’s first direct remarks to the people of China — and likely to be his only such opportunity in a four-day visit. He reached out to the world’s largest online population, saying that individual expression was not an American ideal but a universal right. “We do not seek to impose any system of government on any other nation. But we don’t believe that the principles that we stand for are unique to our nation,” he said.

China’s propaganda tsars may have been displeased with Mr Obama’s comments: they relegated coverage of his first full day in China to the sixth item, some 20 minutes into the half-hour evening news programme, and then devoted less than 60 seconds to his arrival.

It is far from clear that the ideals he raised will come up in his talks with Communist Party leaders, either at a private dinner last night or in formal talks with Hu Jintao today, and the Premier, Wen Jiabao, tomorrow. Disagreements on trade, North Korea, China’s currency, Iran and climate change will dominate the agenda.

Mr Obama seemed eager to get off to a friendly start. “More is gained when great powers co-operate than when they collide,” he said.

Chinese chat rooms quickly filled with responses to his remarks — some critical, many fuelled by Obamania. Some said simply: “How handsome!”

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