Outgunned and unable to attack the European settlement, Yeh Mingchen, the Qing emperor's viceroy for Guangxi and Guangdong, retaliated with a 'terrorist campaign'. Yeh's militia had beheaded 11 Europeans found on the captured steamer Thistle, and there was a 'proliferation of unexplained fires around Hong Kong'. Yeh had placed a bounty on the heads of Europeans, and severed ones (including some stolen from the cemetery in Happy Valley) were displayed in Guangzhou.

'Most households employed a Malay guard armed with a musket to protect them,' writes Hacker, adding that 'British troops supported by French and American sailors patrolled the streets'.

However, on January 15, 1857, no musket could protect the Europeans from the wares of Cheong Ah-lum, who baked most of Hong Kong's bread at the time.

To this day, accounts vary as to who was responsible for the 'great bread poisoning incident' or the 'Esing Bakery incident'. Hacker and G.B. Endacott, author of A History of Hong Kong, among others, have no doubt that it was done on the orders of Qing mandarins. But Jan Morris, in Hong Kong Xianggang, believes that Cheong acted out of his own, patriotic convictions.

'Responding to the wave of xenophobia then sweeping China, [Cheong] decided to exterminate the principal residents of Hong Kong,' Morris writes. 'Since he was the principal baker of the island, he was in a strong position to achieve this, by slipping arsenic into his loaves.'

A clan record of Cheong's lineage, written in 1904 on the instructions of the Qing imperial court and translated by the Royal Asiatic Society's Hong Kong branch, gives another version.

Cheong, a man of intelligence and ability, had 'learned the ways of doing business with the foreigners' from an early age, according to the clan record.

By the time of the poisoning, he was 29 and well respected 'by the Chinese as well as by the foreigners'. After a successful career as a comprador with Murrow, Stephenson & Co, he became a chandler to the European ships arriving in Kowloon. This business included a bakery, which the clan record calls the 'Yu-cheng Bakery'.

According to the clan record, the poisoning was merely an accident. 'Because [Cheong] had too many workers, he had no time to check minute details. One day, through carelessness, he dropped some odd things into the flour. When the westerners bought and ate the bread, they all felt sick and fainted.'

Fortunately for the westerners, those who ingested these 'odd things' immediately vomited up the poison before any serious harm could be done. Among the hundreds poisoned - exact numbers vary - was Lady Bowring, wife of the governor, Sir John Bowring.

The governor - as quoted by Hacker - wrote that the poison 'left its effect for some days in racking headaches, pains to the limbs and bowels' and that his wife 'never really recovered'. Although most accounts of the Esing Bakery incident claimed that no lasting injuries were caused, Lady Bowring left Hong Kong soon thereafter and died in Taunton later that year.

Police arrested anyone connected to Cheong and his bakery staff, and scores of suspects were detained and locked into a small cell. Cheong was brought back to Hong Kong from Macau and his own children were found to have fallen ill with arsenic poisoning.

After governor Bowring stood firm in rejecting calls for Cheong's lynching, Cheong and his fellow accused, who included his father and one of his wives, faced charges before chief justice Hulme. During the three-day trial, the judge and some members of the jury were reported to be still suffering the after-effects of arsenic poisoning, but Cheong and his fellow accused were all acquitted on February 5.

One account states that two bakery foremen who fled to Guangzhou before they could be brought to trial were probably to blame.

Cheong's 'acquittal was a triumph for British justice', writes Hacker. 'What followed was not.'

Cheong was rearrested as 'a suspicious character' and, after protests by 'the leaders of the Chinese community', he agreed to leave the colony in 'voluntary banishment', forfeiting his profitable businesses, including the bakery. One account, in the Lonely Planet guide to Hong Kong, suggests the bakery was taken over by the chandlers Lane, Crawford & Co, founders of the department store chain.

For years after the incident, visitors to Hong Kong called on Cheong's bakery, which Hacker places next to Wan Chai's Hung Shing Temple, on Queen's Road East, viewing it 'as a chamber of horrors', according to Morris. 'A chunk of the poisoned bread, well preserved by its arsenic, was kept in a cabinet in the chief justice's office until the 1930s,' she adds.

Although Cheong disappears into destitution in most accounts of the incident, the clan record recounts a happier ending. After banishment, he prospered in Macau and Vietnam, where he became a consul for the Qing imperial court. Near the end of his life, Cheong received a title from the emperor - 'Hua-ling-tao', which is translated as 'an official who may wear a colourful ribbon'. He died in 1900 at the age of 73, and was buried in his native village, near Foshan.