MM Lee and his wife Kwa Geok Choo celebrate his 80th birthday in Singapore on September 16, 2003. (Reuters)

MM Lee and his wife Kwa Geok Choo celebrate his 80th birthday in Singapore on September 16, 2003. (Reuters)

Reaction from Singaporeans was also swift as news of her death quickly spread on micro-blogging site Twitter.

Some expressed shock such as @hellocharleto, who tweeted, “Omg. Lee Kuan Yew’s wife Kwa Geok Choo passed away. RIP”.

Others conveyed messages of condolences such as @herbertism who tweeted, “Rest in Peace mother of Singapore, Madam Kwa Geok Choo.”

Yahoo Fit-to-Post readers were quick to write messages of condolences, leaving behind over 300 comments in the first few hours of her death.

Among the best-rated comments was one by Chua Kai Shing, who wrote, “Mrs Lee Kuan Yew, behind every success comes an inspirational story. I’m sure we all know you as the great woman behind our beloved senior minister, you are that special someone he chose, and together you are the parents of modern Singapore. Rest in peace.”

Another by Vodka wished that MM Lee would remain strong even after his long-time companion had passed.

“Behind every successful man is a great woman and she had been the pillar of strength for her husband… May her soul now rest in peace. I hope that MM Lee will be strong and keep his motivation for life even though his partner has passed away,” he said.

Madam Kwa was one of 8 children.

A brilliant student at Methodist Girls’ School, she topped the 1936 Senior Cambridge Examination for the whole of Malaya and Singapore.

At Raffles Institution, she caught the attention of a young Lee Kuan Yew when she gave him unexpectedly stiff competition for a Queen’s Scholarship.

Their relationship grew through the Japanese Occupation and by 1944, love had truly blossomed and set in between the two.

Mr Lee left to study law in England in 1946 after World War II and his then sweetheart joined him at Cambridge University a year later.

The two married secretly on 23 December 1947 after she had just turned 27, and he was 24.

Mrs Lee said once: “You can’t explain these things … He had tremendous aplomb, self-confidence, very jaunty, he was a handsome young man.”

When they returned to Singapore in 1950, they tied the knot again, this time with their parents’ full knowledge.

When Mr Lee got more involved in politics and became Singapore’s Prime Minister in 1959, Mrs Lee, her husband and her brother-in-law, Dennis Lee Kim Yew, founded the Lee & Lee law firm in 1955.

She is survived by her husband, two sons and a daughter.

Her eldest son is Lee Hsien Loong, Singapore’s current Prime Minister while her second son is Lee Hsien Yang, chairman of Fraser & Neave and Civil Aviation Authority of Singapore or CAAS.

Her daughter is Lee Wei Ling, head of Singapore’s National Neuroscience Institute.