SINGAPORE - After Japanese troops invaded Penang in 1941, Puan Noor Aishah left primary school, and learnt instead to cook and sew to supplement her family's income.

She peddled nasi lemak with her mother, took orders for embroidery, and visited friends and neighbours to pick up new skills, hungry to make up for the abrupt end to her formal education.

This eagerness to learn helped put her in good stead when her husband Yusof Ishak was made Yang di-Pertuan Negara in 1959. Puan Noor Aishah was just 26.

Her role as the spouse of Singapore's head of state was completely uncharted waters, recalls Puan Noor Aishah in a new book on her life.

"I was not given any instructions or briefing at all; no guidelines on how to be First Lady. I had no task lists and no one briefed me on things like etiquette, dress codes and protocol. We had to learn and manage on our own," she said.

But she swiftly made her mark. She figured out the workings of the Istana, and soon breathed new life into it by teaching its cooks - who were still preparing English classics like roast beef and pudding - her own recipes for local favourites like beef rendang.

She went for English lessons, organised tea sessions for dignitaries and got involved with voluntary organisations. And when her husband's health started to decline after a heart attack in 1968, Puan Noor Aishah shouldered some of his social responsibilities.

Her transformation - from shy housewife to the beloved wife of Singapore's first president - is captured in a 200-page book published by Straits Times Press. Titled Puan Noor Aishah: Singapore's First Lady, it was launched on Tuesday (July 18) at The Arts House by Prime Minister Lee Hsien Loong, who contributed the foreword.

Written by legal scholar and historian Kevin Y.L. Tan, the book also contains photographs of Puan Noor Aishah and her family, including those from her own private albums.

PM Lee in his speech said reading the book brought back memories of growing up in Singapore's early years. He often played with Puan Noor Aishah's three children, and learnt to ride a bicycle from her son Imran.

He still has fond memories of her cooking, he said to laughter, recounting how she spent days collecting over a dozen herbs for her nasi ulam.

"I only had it once, but I remember it till today," said Mr Lee. "I am therefore very happy that we now have a book about Puan Noor Aishah... It will record for generations of Singaporeans her life story, the role she played, and her contributions to our early nation-building days."

Since her husband died in 1970 of heart failure, Puan Noor Aishah, now 84, has kept out of the limelight. So the new book, which costs $25 (excluding GST) at bookstores, offers a precious glimpse into her eventful life.

Puan Noor Aishah was born in 1933, and adopted by Fatimah Ali and Mohammad Salim Jusoh, an Eurasian man originally known as Barney Perkins, who had converted to Islam.

They lived an unassuming life in Penang - until Puan Noor Aishah caught the eye of Mr Yusof. He was then 39, and finally ready to settle down after years of rebuffing matchmaking attempts to focus on his work at Utusan Melayu, the Malay-language newspaper he co-founded.

A close friend coaxed him into looking through photos of potential brides. The last photo was of Puan Noor Aishah.

Something about her face intrigued Mr Yusof, who told his friend: "This one, I agree."

He was whisked away to Penang, where a first meeting was orchestrated. But, recalls Puan Noor Aishah, although her older sister had taken her to a garden one day to meet "a good man", all she did was sit at a table sipping tea. She never saw Mr Yusof that day.

He and his friend were seated somewhere nearby so Mr Yusof could steal glances at her. But, it later turned out, he was too shy to take a good look.

Even so, he wanted to marry her. The couple had their first proper meeting two days later, on their wedding day.

Puan Noor Aishah in the book shares some colourful details about her life with Mr Yusof: His favourite dish was rendang kerang (cockles rendang), and his pet name for her was "Teh", short for "Cik Puteh" (fair-skinned lady).

He helped Puan Noor Aishah along in her quest to learn more, bringing home books for her to read, and arranging for a teacher to help his wife hone her sewing skills.

Their first home together was in a small kampung with no running water or electricity. One day, Mr Yusof, who loved growing orchids ,ended up quarrelling with a neighbour whose cow would wander into their compound, worried it would eat his beloved flowers.

But it was tumultuous times for Singapore, and Puan Noor Aishah and Mr Yusof's lives too would soon be thrown into upheaval.

When the People's Action Party won the 1959 general election, Mr Yusof was founding prime minister Lee Kuan Yew's pick for Yang di-Pertuan Negara.

And so Puan Noor Aishah had to start a new life at the Istana with her husband and three children.

PM Lee in his speech noted how Puan Noor Aishah had insisted that they live simply so that their children's lives could be as "normal" as possible.

Unaccustomed to the grandeur of the Istana, the family chose to live in a small bungalow on the grounds, which had previously been the official residence of the under-secretary of the Straits Settlement.

Mr Yusof called their new home Sri Melati, or Jasmine, and paid for the rent out of his own salary.

Mr Ismail Abdul Ghani, a former houseboy at Melati, notes in the book that the family would eat lunch at the dining table, using porcelain crockery and cutlery, but for dinner, would "roll out a carpet, sit on the floor and eat with their fingers in traditional Malay style, because they wanted their children to grow up knowing their Malay traditions".

And, as the president's wife, Puan Noor Aishah kept these traditions alive in her own way, from putting Malay dishes and kuih on the Istana menu to wearing the kebaya at state events.

She decided on her dress code herself, she recalled: "No one told me what to wear so I had to decide for myself. I thought that the kebaya was nicer (than the baju kurung) so I wore that."

There was no dress allowance for the First Lady, and Puan Noor Aishah did not receive a salary. So she made trips down to Arab Street to buy plain cloth, and would sew and embroider her own kebaya.

She adapted to her new life quickly, said the people around her, including former president Wee Kim Wee, a good friend of Mr Yusof's.

In fact, she transformed the entire tenor and feel of the Istana. During the Colonial era, it was a "staid, stuffy, officious and distant place", the book notes, but by the end of 1960, it became "elegant, traditional, Asian, full of charm, warm and welcoming".

PM Lee said Puan Noor Aishah handled effortlessly the daunting task of managing a large household and carrying out official and ceremonial duties.

"And she touched the lives of many with her quiet determination, humility and charm," he said.

While Mr Yusof did not live to see the country he played an important part in creating develop, Puan Noor Aishah has witnessed Singapore's transformation over the last 50 years, added PM Lee.

"She celebrated SG50 with us, and she should soon see Singapore have another Malay president, if all goes well," he said.

The upcoming election, which will be held in September, is reserved for Malay candidates. This means Singapore can expect its first Malay president since Mr Yusof.

PM Lee said: "I hope it will be a president who will bring as much distinction and honour to the office, and will be as well-loved and remembered by Singaporeans as Encik Yusof."