In April a 1990 speech about how to be a good personal secretary to a senior leader was republished in People's Daily and caused a stir across the mainland. The speaker was a formerly obscure local leader in Fujian province named Xi Jinping. The text was especially memorable because it appeared amid a string of arrests of a dozen former personal secretaries to senior leaders. The Communist Party's top decision-making Central Committee and its disciplinary watchdog - the Central Commission for Discipline Inspection - announced action against up to a dozen senior officials, most of whom were at the ministerial and governor level, on charges of corruption, bribery or abuse of power. The officials punished included Ji Wenlin, former deputy governor of Hainan province; Yu Gang, a former deputy official on the Central Politics and Law Commission; Tan Hong, a Public Security Ministry senior officer; and Guo Yongxiang, former deputy governor of Sichuan province. Also punished were Li Chongxi, the former chairman of the Sichuan People's Political Consultative Conference; Li Hualin, former deputy general manager of China National Petroleum; and Shen Dingcheng, a former party secretary at PetroChina International. All had served as secretaries to Zhou Yongkang, a former member of the party's innermost Politburo Standing Committee and the country's security tsar before his retirement in November 2012. Zhou has also come under investigation. Mainland reports said that investigations were also under way into the activities of four former personal secretaries of Xu Caihou, the disgraced retired vice-chairman of the Central Military Commission. They were General Zhang Gongxian, chief of the Jinan military area command's political department; Li Bin, deputy director of the People's Liberation Army Navy's political department; General Kang Xiaohui, commissar of the logistics unit of the Shenyang military area command; and Qi Changming, deputy chief of staff of the Beijing military area command. The advice in Xi's reprinted speech was not about how to entertain bosses, but counsel to junior officers on how to act more discreetly and not to abuse the role of personal secretary, or mishu , for personal benefit. Not only was the reprint timely, but Xi was also in a position to advise - he served as personal secretary to former defence minister Geng Biao in the 1980s. The arrests raised a bigger issue within the political system: why personal secretaries are often hugely powerful and sometimes just as hugely corrupt. Professor Kerry Brown, director of the China Studies Centre at the University of Sydney, said mishu positions, if abused, could lead to extreme corruption because of the job's exclusive access to leaders. "There is also great opportunity for acquiring independent power," Brown said. Professor Steve Tsang, director of the China Policy Institute at the University of Nottingham in Britain, agreed there was ample opportunity in the posts for abuse of power. "Secretaries of top-level leaders with enormous power over promotion or allocation of resources are well placed to commit corruption because they have opportunities to take bribes to influence the agenda or decisions on such matters determined by the leaders they serve," Tsang said. In Chinese, this influence is known as tong tian , or "access to the emperor". Even in Mao Zedong's era, his wife Jiang Qing had to butter up Zhang Yufeng, Mao's personal secretary. It was widely known that Wang Ruilin, Deng Xiaoping's mishu , was one of the most powerful men in Zhongnanhai during Deng's tenure. The mishu , often chosen by the leader himself, retained his high rank even after the boss moved on to a different post or retired. Today, research by Cheng Li of the Brookings Institution in Washington suggests that, like Xi, more than three-quarters of officials at the ministerial or governor level were once secretaries to leaders themselves. Fifteen of the 25 members in top decision-making Politburo were. So were four of the seven members of the Politburo Standing Committee. Analysts said the statistics reflected the political role the secretaries had played in mainland politics. So much so that they are referred to as the " mishu gang", joining the ranks of the "princeling gang", "Shanghai gang" and "Youth League gang". "With their proximity to the source of power and privilege, secretaries clearly have an inside track for promotion, or even a stepping stone to leadership positions," said Warren Sun, professor of Chinese studies at the University of Monash in Australia. Through nepotism and favouritism, superiors use personal staff to help amplify their power and build up a network of connections and vested interests. At the same time, the secretarial clusters shared the fortune or misfortune of their masters, analysts said. The crux of the matter lies in the one-party system, under which political leaders have enjoyed almost unlimited and unchecked power. That's how the culture of traditional Chinese political patronage comes into full play. And it won't end anytime soon.