But, he said, Tsang had concealed the important details, despite pledging to be “open, [have] candour and [be] above board”.

“Secrecy is the hallmark and stamp of corruption,” he said. Tsang would not reveal it, he said, because doing so would make him “hopelessly compromised”.

The court also previously heard that one of Tsang’s friends paid for the travel expenses of his G4 bodyguard during a private trip to Europe in 2010. The identity of the friend remained unknown to the court.

In a revelation on Tuesday, Perry suggested that it “looked like” the sponsor was Bank of East Asia chairman David Li Kwok-po, whose name has turned up occasionally in the trial.

The bank chairman was a shareholder of the radio station in question, and was said to have given Tsang and his wife an unexplained HK$350,000 sum prior to Tsang’s Europe trip.

The prosecutor said travel records showed that Li was out of town when Tsang was in Europe, and only returned a day after the former leader’s arrival on August 7 in 2010.

Tsang, 73, has denied one count of accepting an advantage between 2010 and 2012 as the chief executive.

The prosecutors’ closing speech marks a step closer to the looming verdict, which the jury could return as soon as Thursday next week, when it is expected to be sent out for deliberation.

Donald Tsang’s wife deposited HK$350,000 cash just after bank chairman withdrew same amount, trial hears

The prosecutors have said the top official had accepted free, tailor-made refurbishment for a three-storey penthouse on the mainland, where he planned to retire temporarily.

In return, they said, Tsang became “favourably disposed” to Wave Media, a local broadcaster, whose majority shareholder was Bill Wong Cho-bau. Wong owned the penthouse in Shenzhen via a company and footed the renovation bill, the prosecutors said.

They said Tsang had granted various applications, including a digital broadcasting licence, to Wave Media when he was chairing the Executive Council, the city’s top advisory body, at the time.

But on Tuesday, Perry told the panel of nine jury members that regardless of the applications, they could convict Tsang as long as they were sure he had been “sweetened”.

The court also heard earlier that the rules governing the declarations of interest of Tsang’s subordinates did not apply to him. But, Perry said on Tuesday, being the “paragon” of the administration, Tsang would have been aware of the standard that even “the most junior civil servant would know”.

Since the press became sceptical about the former leader’s conduct in February 2012, Tsang had gone on to radio programmes and written an article in the Sunday Morning Post to talk about integrity, the prosecutor said.

But Perry stressed on Tuesday that the top official had never made known his connections with Wong, Li and another Wave Media shareholder, radio personality Albert Cheng King-hon. While Li, the prosecutors said, gave Tsang and his wife HK$350,000 at one point, Cheng was the person who introduced internationally renowned designer Barrie Ho Chow-lai to work on the renovation.

The amount paid by Li to Tsang and his wife happened to match the amount Wong paid the designer as the service fee for the Shenzhen penthouse, Perry highlighted to the jury.

Bank records have shown Tsang paid Wong’s company 800,000 yuan in 2010, some 20 months before a lease for the penthouse at East Pacific Garden was entered into in 2012. Until now, Perry said, Tsang had stopped short of offering an explanation as to how a rental payment, if it was, could be calculated months in advance. Instead, he said it was Tsang’s attempt to buy the penthouse at an undervalued price.

Jurors in trial of former Hong Kong leader Donald Tsang ordered not to work on Saturdays

These were all “key facts”, the prosecutor said. But instead of revealing them, Tsang misled the public by suggesting that there was an increased expectation from the public for officials that led to media scrutiny of him, and that therefore he would focus on improving certain rules, Perry said.

“Are you happy about what you see?” he asked the jurors.

Tsang chose the Shenzhen penthouse, Perry said, because he wanted a place “suitably grand” that would reflect his “status as a former chief executive of the region”.

“How is he going to do that? Of course, it helps when you get rich friends,” he said.

He cautioned the jurors to exercise their judgment when it came to deciding whether a witness was credible, naming two officials in particular, former permanent secretary of Tsang’s office Kenneth Mak Ching-yu and then deputy private secretary Kevin Choi. He said they had stopped short of giving straightforward answers, even though they were prosecution witnesses.

The prosecutor is expected to finish his speech on Wednesday before Mr Justice Andrew Chan Hing-wai.