When Mr Lee Kuan Yew turned purple after choking on a piece of meat during lunch, it was his personal security officers (PSOs) who saved his life.

They helped the late Mr Lee dislodge the piece of meat, recounted his daughter, Dr Lee Wei Ling, 60.

"By that time, Papa had already turned purple. But within seconds of the meat being dislodged, he was mentally alert," Dr Lee said at her father's cremation service at the Mandai Crematorium last month.

Speaking fondly of the PSOs, Dr Lee said they formed an integral part of her father's life, even more so in the last five years.

When Mr Lee developed Parkinson's disease three years ago, it became difficult for him to stand and walk. It was the PSOs who helped him along when he refused to use a walking stick or a wheelchair.

Even outsiders could see how attentive the PSOs were. "One doctor friend who came to help dress a wound Papa sustained when he fell noticed this and said to me, 'The (PSOs) look after your father as though he is their own father'," Dr Lee said.

She added that her relationship with her father's PSOs was "as understated as plain water", a literal translation from a Chinese idiom which means they would help each other without obligation when needed, even before a request for help was made.