Even basic facts are in doubt, including the date of his death. Some witnesses claim Lao She left his home early on the morning of August 24, walked to the lake and drowned himself. Yet his son, Shu Yi, says another witness, a worker who lived near Taiping Lake (which no longer exists) discovered the body early on the 25th.

'He may have sat by the lake hesitating for 24 hours before finally loading his pockets with stones and wading in,' Fu says.

On August 24, he was under orders to report to the Beijing Writers' Association and to wear a placard identifying him as a 'counter-revolutionary in motion'. It is therefore not clear, says Fu, where he went after leaving his home. There is no forensic evidence to confirm the cause of death. His corpse was taken straight to Babaoshan, the cemetery in western Beijing where the communist leaders are buried, and cremated. His widow was not even allowed to collect his ashes because he was regarded as a counter-revolutionary who had killed himself.

That so many questions continue to be aired so publicly is striking when he is regarded as Beijing's patron writer. Tourists visit the Lao She Teahouse, and have their photograph taken on Wangfujing shopping street in a bronze statue of a rickshaw being pulled by Camel Xiangxi, one of Lao She's most famous characters.

They visit the Lao She Museum, which opened this year in his former courtyard house close to Wangfujing, see his plays, attend the Lao She film gala, or read books selected in the biennial Lao She Memorial Literary Prize. Only a proposal to erect a statue in his honour at the place of his death has been rejected.

The son of a Manchu bannerman, Lao She grew up among Beijing's poor, struggled to educate himself and then taught at the London School of African and Oriental Studies in the 1920s, living in lodgings off Russell Square. When he returned to Beijing in 1930, he taught in Jinan University until he fled the Japanese, drifting to Chongqing, the Kuomintang's wartime capital, and finally ending up in New York from 1946 to 1949.

His works, mostly set in Beijing, became popular. As a neutral player in the fierce battles between the left-wing writers' groups and their opponents, he was chosen to head the United Writers' Anti-Aggression Front, which opposed the Japanese invasion.

After the then premier, Zhou Enlai, personally invited him to return to Beijing in 1949, he worked hard to adapt to the limitations laid down by Chairman Mao Zedong in his 1942 Yan'an talks, in which it was stated the purpose of art was to promote the proletariat revolution. Lao She's last work was about pig farming in a people's commune. He said nothing of the massive famine that cost more than 30 million lives, or the purges that destroyed his friends and colleagues.

The Chinese Communist Party praised him as the 'people's artist' - yet, according to his wife Hu Jieqing (who died this May, aged 96), Zhou rejected his application to join, telling him he was more valuable endorsing its actions on the outside.

After 1949, the party set out to bring the intelligentsia under control and the literary community was split between those who had gone to Yan'an after 1937, and taken part in the literary purges there, and those who had gone to Chongqing, Hong Kong or abroad. The latter bore the brunt of the campaigns in the 1950s, especially the Anti-Rightist Movement. In the Cultural Revolution it was the turn of party loyalists such as Lao She to suffer; the others were largely left alone.

Fu's book, which records contradictory testimonies, casts an ugly light on many senior figures in China's official literary circles. All accounts agree that the 66-year-old writer went to the offices of the Beijing Writers' Association in the city's Bureau of Culture. From there he was taken by truck with 20 others to the Temple of Confucius.

About 150 uniformed schoolgirls from the Beijing No 8 Middle School (renamed the Lu Xun Memorial School) were already there and had been briefed for an hour beforehand on their task. In the inner courtyard, a bonfire was burning, destroying theatrical props taken from Beijing opera groups.

When the writers arrived, they were pushed through a human tunnel of teenage girls screaming 'beat the blackguards', and waving sticks and fists. For at least three hours, the writers knelt before the fire while the girls beat them with such props as swords, halberds, belts and bamboo sticks. Then, they hung placards stating their crime around the writers' necks as an official photographer recorded the events.

The victims were then trucked back to the Culture Bureau, some say at 5pm, others say at 8pm. There, the beatings continued. Lao She resisted wearing the placard and this enraged his persecutors, who even attacked a car that arrived to take him to the safety of a nearby police station.

Even there he was not safe. The furious crowd climbed over the wall and continued beating him until midnight. Police eventually telephoned his wife, asking her to collect him. She struggled to find help until, ironically, found one of the last remaining rickshaws left in Beijing.

Why did he attend the 'struggle session', and who organised it? His wife claimed he went voluntarily and Fu believes the party never intended to criticise him. However, Kang Sheng, the Torquemada of the purges and head of the secret police, did telephone Lao She inviting him to a meeting and to participate in the Cultural Revolution.

'The Cultural Revolution is a revolution to touch everyone's soul, how can I not go?' Hu quoted her husband as saying before he left.

Who, then, ordered his persecution? According to the Red Guard leader, someone from the Writers' Association had called her the morning of the beating ordering her to ready her group to 'make rebellion'. The woman, now a school janitor, claims the girls had no idea who the victims were or what crimes they had committed.

No one admits to ever having made this phone call. There are three suspects, however, who ran the revolutionary committee in the Writers' Association. Two of them, Hao Ran and Cao Ming, belonged to a younger generation of writers who rose to power by taking part in the 1942 Yan'an Forum. A third is Hou Wenjun, a graduate student from Beijing University.

Lao She's son, Shu Yi, believes these younger writers hated Lao She because he consistently declined to write introductions and endorse their propaganda novels. Witnesses claim all three instructed the students to single out Lao She and incited them by saying he was not accepted into the party membership because he was disloyal to Mao, and that he had accepted money by selling the rights of Camel Xiangzi.

Why Lao She reacted to the humiliation by taking his life when other victims - such as Xiao Jun, who suffered as badly if not worse - did not, is a painful question for his family. Suicide among scholars is traditionally the ultimate protest against the emperors' policies, yet many intellectuals preferred to endure everything to protect their families.

Shu believes his father's actions were deliberate, that he chose Taiping Lake because he had bought a house for his mother there and wished to be close to her. Yet he is still unsure of his father's motive and insists he remained a true believer in Mao, even taking a copy of his poems with him to his death. Those suspected to bear responsibility for his death counter with the claim that Lao She killed himself because of tensions at home.

'Hao Ran has said that if the family of Lao She had treated him better, Lao She would never have committed suicide,' says Fu.

Cao Ming alleges Lao She's wife responded coldly to the news of her husband's death saying 'he's died, so he is dead'. Cao has also publicly dismissed its significance by writing that 'many people committed suicide [at that time] but he just happened to be famous'.

Although the Cultural Revolution was condemned by the party after 1978, Cao's career flourished, as did those of Hao and Hou Wenjun. Cao continued as a senior figure in the All China Writers' Association and delegate to the National People's Congress until her retirement a few years ago.

Lao She (left) was praised as the 'people's artist' by the Chinese Communist Party, but never joined. Author Fu Guangming (below left) stands next to a statue of Lao She and other writers.