Leading article: What this mysterious death says about China

For a death that went almost unreported at the time, the fate of Neil Heywood, a British businessman based in China, is turning out to have far-reaching repercussions – for Chinese politics, for bilateral UK-China relations and, in the most salutary fashion, for the wider public perception of China. Mr Heywood died in early November in a hotel in the booming city of Chongqing. Since the closure of China's National People's Congress last month – one prelude among many to a 10-yearly leadership reshuffle – not a day has passed without some new detail emerging.

For all the information that has come to light, however, only a few facts seem beyond doubt. One is that Neil Heywood died in Chongqing at the early age of 41, leaving a wife, who is Chinese, and two children. A second is that his body was cremated shortly afterwards. Another is that he was closely associated with a leading Chinese politician, Bo Xilai, who was then the Communist Party leader in Chongqing. And the last certainty is that Mr Bo recently fell into official disfavour in Beijing and was last week stripped of all official positions.

Many other details, though, seem either fanciful or contradictory. The initial cause of the Briton's death was given as alcohol poisoning or a heart attack. Most recently, a supposedly reliable blogger said it was cyanide. What was first reported as a natural death had already been reclassified as a murder, with Gu Kailai, Mr Bo's businesswoman wife, named as the chief suspect. But it is unclear whether the accusation against Ms Gu predates or postdates her husband's political difficulties.

Is it cause, or might it rather be effect? The latest claim is that Mr Heywood and Ms Gu were romantically linked, and that either romance or business turned sour.

Similar mystery surrounds the past actions and current whereabouts of the local police chief, Wang Lijun, His failed attempt back in February to claim asylum at the regional US consulate – and perhaps at a British consulate, too – might have been the first warning of a criminal aspect to Mr Heywood's death, if some dots had been joined up earlier. But even the allegation against British diplomats – that they showed scandalously little curiosity about Mr Heywood's death in order not to jeopardise relations with Asia's rising power – or, perhaps, because of his rumoured intelligence work – seems less clear-cut, once you learn that a British diplomat was at his cremation and a Foreign Office minister went to Chongqing two weeks after his death. Officially, that was part of a trade tour, but – with hindsight – who knows?

With timing and motives so jumbled, it will be a wonder if the facts ever come out – and, with so much speculation in train, we might not even recognise it if it did. This unsettling episode, though, points up two truths. The first is that, whether or not the Foreign Office showed sufficient interest early on, the case has become at very least an irritant in UK-China relations. Beijing needs to come clean about what happened and allow Mr Heywood's widow to leave the country, if that is what she chooses to do.

The second concerns the glimpses that this saga affords of the way China functions. China's rapid rise has fostered an often starry-eyed view of its wealth and prospects, in Britain, as elsewhere. Chinese money is welcomed abroad, without too many questions being asked about its provenance.

The reality is that China is a one-party state whose superficial prosperity cloaks endemic corruption and ruthless politicking. That politicking is likely to become more desperate as the autumn leadership changes approach.

Bo Xilai, an ambitious politician with a model revolutionary pedigree, is an early victim of the struggle. While many changes in China have been for the better, it is as well not to succumb to illusions. There is a murky and lawless side to its development that Mr Heywood's untimely death has exposed.