The notorious 'four great Chinese sergeants' - among them Hon Sum - began their corrupt reign in the 1960s.
They were all police staff sergeants, a post that has since been abolished, and were in their posts for years, unlike today where officers are rotated.
As officers on beat patrol had close contact with gambling, prostitution and other organised crime, the very nature of their job offered ample opportunities for graft. Those who refused were ostracised or pressured to leave.
But, as a retired customs officer explained, this was made worse by the organisational structure of the police force, in the form of the staff sergeant and sergeant major. 'A staff sergeant, while being lowly on the organisational chart, actually exercised enormous power,' he said in an interview with the Post yesterday on condition that he not be named.
'You didn't have a choice. If you refused to take bribes, you were thumbing your nose at your superiors, you would be upsetting careful arrangements maintained between crime and law enforcement - upsetting the balance, so to speak.'
There were three or four staff sergeants at any one time, and they were in charge of all the rank-and-file officers in their areas. Unlike today's division by districts, they were responsible for huge geographic areas - Hong Kong Island, Kowloon - Yau Ma Tei had its own sergeant - and New Territories. A sergeant major lorded over them.