“If this public forum can only be held with the government or myself promising that Queen’s Pier will not be relocated or demolished, I am sorry, I cannot make such a pledge,” Lam said.

“We cannot think that a new minister taking office means she can change historical facts.”

While her statements sparked calls for her to step down, her decision to show herself at the pier drew approval.

The episode underlined the career bureaucrat’s tough, no-nonsense style – that she is not someone to barter principles for popularity. That baptism of fire at the pier also earned her a reputation of being a “good fighter”.

However, the popularity ratings of the two – who are set to become arch-rivals in the city’s leadership race in March after Lam tendered her resignation on Thursday – took an interesting twist during the 79-day pro-democracy Occupy protests from September to December 2014. Tsang began to emerge as the more popular of the two.

In October 2014, almost a month after protesters brought parts of Hong Kong’s business hubs to a standstill to protest against Beijing’s stringent rules on reform, Leung sent Lam to negotiate with student leaders.

On that critical night, Lam maintained it was impossible to reverse Beijing’s decision, even as she promised to write to the central government about the widespread negative public sentiment.

“Hong Kong cannot decide on its own its political development,” she said.

Once again Lam showed she would not shun from making an unpopular call when needed.

A source told the Post that around that time, Lam invited more than 20 political scientists and thinkers to her home to discuss political reform, along with several students. The dialogue over dinner became heated at times, but Lam stood her ground.

“There was finger-wagging at Lam but she stayed firm and remained quite calm,” the source, who was present, said.

Dismissing suggestions that the deal was part of her campaign bid, Lam launched a thinly veiled attack on Tsang, saying: “I understand that, before, during or after elections, it’s best not to have controversies ... because that’s the way you win popularity.”

The meeting came a month after Lam’s announcement on December 10 that she would “reconsider” running for the top job less than 24 hours after Leung’s decision to bow out – a surprise U-turn given she had earlier repeatedly denied any ambition to be chief executive.

Lam has been no stranger to controversial or difficult decisions during her career as a mandarin.

After graduating from the University of Hong Kong, where she was an active member of the student union, Lam joined the government in 1980.

She showed her no-nonsense approach to meetings and minutiae when she became director of social welfare in August 2000. A former civil servant who worked at the Social Welfare Department recalled how Lam displayed her iciness at her first regular meeting with unit heads.

“When the others were passing around a sheet jotting down what to drink – lemon tea, milk tea and so on – when someone gave it to her, she calmly raised the paper and tore it apart,” he recalled.

As welfare chief, Lam introduced several reforms, such as tightening the social security assistance scheme and making it available only to people who had lived in Hong Kong for more than seven years – not new immigrants.

The change was eventually overturned by Hong Kong’s top court in 2013 after a lengthy legal battle.

From 2003 to 2004, Lam served as permanent secretary, or the top civil servant, under Michael Suen Ming-yeung, who was then secretary for housing, planning and lands.

Writing on his blog on the AM730 newspaper on Wednesday, Suen said while Lam was willing to listen to dissident voices, she also “often showed a rather icy character ... and had extremely high standards for herself and others”.

“I think successful leaders are willing to entrust their subordinates with tasks ... and not require them to be the same as themselves. I am sure that Lam will seriously work on that if she wants to advance on her career,” Suen wrote.

Lam’s critics, especially pan-democrats, lament her tough style, saying it would not help Hong Kong heal after five years under a divisive figure like incumbent Leung.

Civic Party lawmaker Tanya Chan believed that Lam had changed since the end of the Occupy protests.

“I was there on July 29, 2007, and Lam was the only official who dared to meet her critics when no one else did. In October 2014, at least she was willing to try to engage the students in a rather alternative way,” Chan said. “But now it seems she has distanced herself from the crowd … and deliberately got around the procedures to secure the museum deal. This was terrifying to me.”

Chinese University political scientist Ivan Choy Chi-keung said Lam’s handling of the Palace Museum controversy had put her on a bad footing.

“Society yearns for reconciliation and hopes confrontation and division can be minimised. People are not against the building of a museum, but in the press conference on Tuesday, Lam even refused to give a hint on whether anything could be improved in her handling … and quickly turned to say that the deal has offered ‘more bullets’ for critics,” Choy said.

“It made people feel that she is very combative. I fear even if she wins the top job, it will be difficult for her to lead society in reconciliation, especially between the government and the pan-democrats.”

Whether or not she can lead such a healing process, Lam seems to have her armour ready. Two years ago she quoted the Bible about facing the wrath of the public in making right but unpopular decisions.

“‘Blessed are those who are persecuted for righteousness sake: for theirs is the kingdom of heaven’ – there is already a place reserved for me in heaven,” she declared.

Critics accused her of arrogance. But even they accept that come March 26, if Lam wins the chief executive race, she will need all the help she can get – including from heaven. After all, the lion’s den she will be entering will be a much bigger one than a pier.

Additional reporting by Stuart Lau