This week I tried to visit Zeng Jinyan, Chinese blogger, wife of the detained dissident Hu Jia and mother of an infant daughter. I did not get far.

Near the door of Ms Zeng's apartment block in the paradoxically named Bobo Freedom City compound near Beijing, I was stopped by a police officer and half a dozen plain-clothes security agents. The officer politely explained that I could not meet Ms Zeng without her prior permission. He was unmoved by my objection that authorities had made such permission difficult to obtain by cutting off Ms Zeng's home telephone line and her access to the internet.

Such authoritarian catch-22s are a staple of the ruling Communist party's tenaciously maintained monopoly on political power in China. By arresting Mr Hu on sedition charges and keeping Ms Zeng under virtual house arrest, the party has demonstrated its determination to crack down on dissent ahead of the Beijing Olympics in August.

But while a simple security cordon was enough to stymie this foreign correspondent, some of Ms Zeng's would-be visitors are less easily cowed. In recent internet accounts, anonymous sympathisers have told of their attempts to show solidarity with Ms Zeng by bringing gifts of infant formula for her daughter.

In one, a well-wisher recounts how turning up at Ms Zeng's gate leads to hours of detention and interrogation in a freezing, cigarette-smoke-filled local police station. Although upset, the blogger reflects that such short-term suffering pales beside the travails of Mr Hu, whose campaigns for Aids victims and other disadvantaged groups made him a prime target for authorities long before his arrest. "Freedom is so precious, but Hu Jia gave up his personal freedom for us," the blogger writes.

But the most creative of these acts of restrained defiance is the remarkable "professional-level milk powder delivery operation", described in a richly detailed and almost lyrical account of a two-day attempt to smuggle two bags of infant formula past the police.

Reproduced with an English translation on the www.globalvoicesonline.org website, the account is a very 21st-century affair, melding text with edited Google Earth images, digital photos and a link to the YouTube video site. The milk powder emissary describes skulking nervously around the compound in the middle of the night to find a way past the waiting security agents. "Who is the more free?" he wonders. "The police dogs leashed and led with iron collars, or the prisoner that the howling police dogs constrain?"

In the end, the emissary manages to make remote contact with Ms Zeng and to pass the infant formula to her mother, a feat that meets his criteria for success and allows him to leave the scene happily singing a song by the US heavy metal band Metallica.

It would be easy to overstate the import of such victories. A Communist party empowered by China's economic growth and growing global stature can easily shrug off individual challenges to its authority. The Olympics will offer critics an opportunity to highlight abuses of human rights, but such issues are well down the diplomatic agenda of western powers anxious to engage rather than alienate Beijing.

Indeed, Mr Hu's jailing demonstrates China's continued ability to act against its internationally recognised dissidents. And while the internet is easily China's freest public space, the party's surprisingly effective censorship system means only a tiny fraction of those online will ever hear of the milk powder missions.

But such accounts still stand in revealing contrast to the stale theatrics of this month's annual session of China's docile parliament, the National People's Congress. While the NPC's carefully chosen delegates vie with each other to express approval for their leaders' world view and policies, the milk powder emissaries show that, for some Chinese, the party's ideological underpinnings are an irrelevance.

In his speech to the NPC's opening session, Wen Jiabao, the premier, told delegates the government would "expand people's democracy" and that they should "liberate their thinking". For Mr Wen, however, such phrases are code for tinkering with the lower reaches of the political system and for embracing new approaches to econ­omic growth.

The last thing the party wants is for its subjects truly to embrace democratic free-thinking. The "professional-level milk powder delivery operation" is a reminder that some of them already have.

The writer is the FT's Beijing ­correspondent