"At the time, we were an adjunct of the British Red Cross," says Marden, 87. "We started a school for physically handicapped children. Back then, if you started with everything working, you had a chance of making good. But if you had a disability of any kind, it was very different. The school was in Kwun Tong, which in those days was an empty hillside. We took in children who could benefit from an education."

It was Hong Kong's first special-needs school, which is today known as the Princess Alexandra Red Cross School. "The Red Cross was very small then. We used to go wherever we were needed," Marden says.

When fires broke out in the squatter areas, she and her colleagues would hand out clothing and blankets to people who had lost everything.

"I remember Typhoon Wanda [in 1962]," she says. "The whole school was rocking … The children had to sit up all night singing songs because of the typhoon roaring outside. The effects of typhoons were very different then."

In the mid-1970s, Vietnamese refugees began pouring into the city, often arriving on leaking, unseaworthy boats. Between 1975 and 1999, 143,700 Vietnamese refugees were resettled in other countries and more than 67,000 were repatriated, according to the Immigration Department.

"I was interested in the Vietnamese children," says Marden, who has four children of her own. "My daughter-in-law Elaine got her father, who worked with a bus company, to lend her a bus, and she took the Vietnamese children out to Big Wave Bay. She did that just once, but I thought it was such a good idea that I took it on."

She then started taking the children on weekly trips to the seaside, and tried to ensure all of them had the opportunity to go on an annual trip. That was the beginning of Treats, a charity focused on integrating children into Hong Kong society that is still going strong today.

"Then the government started putting the Vietnamese children into closed camps," Marden says. So she began working with the International Social Service to provide the children with education in those camps. "They were in those Nissen huts, which were so terribly hot … It must have been so uncomfortable," she says. "Initially, we taught the children subjects in English."

But as it gradually became apparent that thousands of them would be repatriated, "we started to teach them Vietnamese instead to prepare them".

Marden has been involved in a number of charities from their beginning, including the Playright Children's Play Association, formed in 1987, which fights for children's rights, including their right to play in a city tied down by educational pursuits.

"What we are trying hard to do is to get a children's commissioner," she says. "Children don't vote and their interests need to be represented. Most countries have a children's commissioner, who would put the child's needs first in government policy."

More recently, Marden's attentions have turned to the issue of human rights through a family connection, when her granddaughter married a Tibetan man.

"He joined a demonstration and was put in prison and badly tortured. It was Amnesty International that got him out of prison," says Marden.

He later escaped to Kathmandu, where he now lives with his wife and three children. "He's still suffering. When you've been tortured, you never get over it," she adds.

Marden now supports Amnesty International and also funds the annual Human Rights Press Awards at the Foreign Correspondents' Club.

After decades of non-stop aid work, she entertains thoughts of a quieter life. "The queen and I are the same age [at 87 years old]," says Marden. "She can't retire, but I will."