Yet, more than a week after the public has been told of expensive banquets and gifts showered on mainland officials by our former top graft-fighter Timothy Tong Hin-ming, you have not said a word.

For the good of yourself and Hong Kong, this silence must end.

Put together a high-level committee to investigate this accusation and review the internal controls of the Independent Commission Against Corruption. Show zero tolerance of corruption.

It won't be an easy call.

Your advisers are not short of conspiracy theories behind the detailed revealing in the media of Tong's misbehaviour.

Tong has been retired for almost a year now so what took the whistle-blower so long to act? Why didn't the media say anything until Tong was appointed to the Chinese People's Political Consultative Conference by Beijing last month?

Who is the "boss" of Tong in Hong Kong and Beijing? Who and what is the real target of the whistle blower?

Is it a plot by the liberal camp to undermine Beijing's authority? What role does the chief executive of the Democratic Party, who happened to have worked at the ICAC during Tong's tenure, play in this?

You must have heard some of these questions, I know I have.

They said Tong's HK$1,200 per head banquet, HK$4,100 worth of stone sculptures and mooncakes for mainland officials were too "cheap" to be considered bribes on the mainland. Mooncakes are cut up not to be eaten but to check for gold and diamonds, so the saying goes.

Or as one of your allies put it: "You can't buy a CPPCC seat with a piece of stone. It costs millions of yuan."

In short, the political stake at risk is too high while the "guilt" of Tong is too trivial to justify any action.

We have heard Zhang Xiaoming, the director of the Central Government Liaison Office, saying that "it's normal" for Tong to buy his staff more than 22 banquets over five years with public money.

This is only a month after Zhang issued a directive to his staff of going to fewer banquets and accepting no gifts as part of President Xi Jinping's anti-corruption drive.

We have heard legislators with Beijing affiliation saying they "saw no urgency" in discussing the scandal in the legislature and in setting up a select committee to investigate it as proposed by the liberals.

This measurement of cost and guilt cannot be more erroneous.

No political cost is too high to pay when it comes to fighting corruption in Hong Kong. This is the last competitive advantage Hong Kong has and the last thing our men and women are proud of.

No guilt is heavier than a top graft-buster bending the rules to shower someone with goodies.

Who benefited from them, how much did they cost, and whether Tong gained any advantage in return does not matter.

Tong had been able to buy banquets, mao-tai liquor and gifts for "business contacts" in the name of the commission of his own free will. He had them paid for with public money by playing with the numbers.

The spending on bird's nest and cookies was withheld from legislators' scrutiny by the commission because "they are not classified as gifts".

This has brought into doubt not just the integrity of Tong but that of the ICAC as well as your promise to keep Hong Kong clean.

Unlike the illegal structure at your home, this will not be forgotten as the media gets busy.

It will be raised by the men and women in the commission when asked to stay another hour to go through more documents.

It will be raised by a young accountant when offered a handsome bribe to sign off on a cooked-up book.

It will be raised by a young fund manager when asked to buy some stakes in a faulty mainland firm in return for a rebate.

It will be raised by our competitors who will not hesitate to portray us as just another corrupted mainland city.

Only bold action from you can remove the doubt and help young men and women to say no to temptation.

It takes courage to put politics aside. It takes courage to fight corruption. Your predecessor Donald Tsang Yam-kuen may not be a good example of this.

Yet, he had the decency to ask retired chief justice Andrew Li Kwok-nang to head an independent committee to look into his own wrongdoing and advise on further scrutiny when caught receiving favours such as the yacht trip and a cheap flat.

That is the least you could do.