Leading article: Ai Weiwei is free; another 1,426 are not

It would be good to think that the Chinese artist and dissident, Ai Weiwei, had been released because of the sustained pressure from the world's human rights activists. Mr Ai has, under the terms of his bail, said nothing, but his demeanour is not that of a man whose spirit has been broken into demonstrating a "good attitude in confessing his crimes", as the Beijing police suggested. Having said that, thousands of political prisoners remain in Chinese jails. Among them is Liu Xiaobo, last year's Nobel peace laureate. His empty chair at the Nobel ceremony in Oslo spoke eloquently of the problem. But the vast publicity which ensued appears to have done little towards securing his release.

It may be that the authorities in Beijing felt that the release of one man ahead of the Chinese premier's visit to Europe was sufficient. But they may simply believe that the artist is less of a threat to their domestic political stability than are Liu Xiaobo and other jailed pro-democracy campaigners. As China's economic power increases, its readiness to observe human rights appears regrettably to be diminishing. At the last UK-China human rights exchange, the Chinese, confronted with London's concerns, batted back questions about overcrowding in Britain's prisons, the age of criminal responsibility in the UK and the tensions between the majority population and the nation's ethnic minorities.

It is important to be realistic about the nature of relations between China and the West. But it is also vital not to be cowed into silent acquiescence. David Cameron should this week take a break from the task of finding ways for our two countries to benefit from economic complementarities to congratulate the Chinese political establishment on its release of Ai Weiwei. He should then ask about the other 1,426 individuals known to be languishing in Chinese jails for political or religious reasons.

Liu Xiaobo should be at the top of that list. Mr Cameron should make it clear that the world would applaud his release just as heartily as that of Ai Weiwei. And the applause would grow, the more political prisoners followed him out of China's jails.