There, she faced down powerful forces working to undermine the council, former colleagues have said.

Companies threatened to sue, but the chief executive never bowed and would just "laugh things off", said Professor Ron Hui Shu-yuen, who worked with Lau at the council for six years.

"She does not do favours for anyone," he said, describing Lau as industrious, upright and with an eye for detail.

One case which especially struck him was her hardline criticism in 2006 of the use of hydrophilic polyacrylamide gel (PAAG) in plastic surgery. The gel was legally used in procedures on the mainland, but Lau was determined to give consumers a warning. PAAG is classified by the International Agency for Research on Cancer as probably capable of causing cancer, and had adverse health effects on local patients who underwent facial makeovers on the mainland.

"We were worried about lawsuits [brought by mainland hospitals]. But Connie insisted the council should speak out," Hui recalled.

In the end, PAAG was banned on the mainland following the council's warning.

When Lau left the council two years ago, government officials told members about their bittersweet relationship with its chief, Hui said.

It was a lot of pressure working with her, but she also drove authorities towards improvement, they told him. The Centre for Food Safety, for example, started to do more food testing following the council's initiatives; the increased schedule has now become routine.

Lau has never worked in government, but Hui thinks her lack of experience could be a plus. "As an outsider, she would be able to spot things which are wrong but have become the norm."

Fellow council member Thomas Cheng also has confidence in her integrity. Whatever decision she makes is free from any external influence, he said.

"It is rare that you can trust someone's integrity 100 per cent. But Connie is one such person," he said.

Lau is able to put herself in complainants' shoes and will be sympathetic to the difficulties the public face dealing with government bureaucracy, he said.

Michael Wu Siu-ieng, chairman of the Travel Industry Council, said the public's confidence in Lau makes her a good candidate for the post.

"To head a watchdog, you should have a good track record of neutrality," he said. "It is especially important for the Ombudsman, as it hears complaints from those who are treated unfairly by the government."

Having handled travel complaints together with Lau, Wu described her as a fair person.

"Connie speaks on facts and doesn't judge people," he said.

Back in 1974, Lau was a fresh sociology graduate from Chinese University when she joined the Consumer Council seven months after its creation. Some of the complaints dealt with then were as simple as fried beef noodles having too little meat.

Times have changed and grievances have evolved - complaints against telecommunications services now top the list of issues the council must deal with. In 2008, more than 10,000 complaints about complex investment products poured in to the watchdog following the bankruptcy of the US investment bank Lehman Brothers.

Under her stewardship, the council advocated for legislation to protect consumer rights. The Competition Bill, Residential Properties (First-hand Sales) Bill, and Trade Descriptions Bill were subsequently passed.

On reaching retirement age, Lau had planned for some free time when she left the council.

But her holiday was cut short after the United Nations tapped her to become the first chairwoman of its International Advisory Group of Experts on Consumer Protection.

Lau helped to revise the UN Guidelines for Consumer Protection, first introduced in 1985. The document had been used by various countries as a basis for their consumer protection laws, but had not been revised since 1999.

Lau will give up her UN title, as well as some 10 other posts, for the role of Ombudsman.

She believes the same gatekeeper spirit drives the council and the Ombudsman role.

"I fought for consumer rights. Now I strive to ensure citizens enjoy quality service from the government," Lau said.

Connie Lau

Graduated from Chinese University's sociology programme. Joined the Consumer Council

Became chief executive of the Consumer Council

Retired from the council. Appointed chairwoman of the UN's International Advisory Group of Experts on Consumer Protection

Appointed as the new Ombudsman for a five-year term starting next month