An emotional Sir Keir Starmer opened up about his mum's death, describing the moment he saw four nurses rushing to save her life.
The Labour leader told party conference he remembers seeing her in an intensive care unit, her bed "a riot of tubes and temperature devices".
"I could sense the urgency in the conversation of the four nurses on my mum’s bed," he said.
"I knew without being told that they were keeping her alive.
"I can hardly convey to you the emotion of seeing your mum in that condition."
Sir Keir's mum Josephine Baker was diagnosed with Still's disease as a youngster.
The condition is a rare form of inflammatory arthritis which severely restricts mobility.
As his wife Victoria watched, he also spelt out more about his personal life to the audience in Brighton.
He felt a moment of "horrible irony going to visit his mum in hospital wanting to tell her about his achievements without knowing she was fighting for her life.
"I had just picked up an award for work on the death penalty I’d been doing which in my own small way was about trying to save people’s lives.
"I’d gone to the hospital hoping to tell my mum about it. And there in front of me, those four nurses were working to save her life."
Ms Baker died just two weeks before Sir Keir was elected as an MP for Holborn and St Pancras in 2015.
The Labour leader lifted the lid on his personal life in the "most important speech of his life".
He said family and work are the two rocks of his life, with his tool maker dad who gave him "a deep respect for the dignity of work".
"Every time I enter a high-tech factory, I wonder what my dad would make of it.
"Not so long ago we shaped metal by drilling it, milling it and turning it.
"I remember my dad working with a spark eroder submerging metal in liquid and using an electrical charge to shape it."
And his mum who gave him "an ethic of service" even though "my mum was also, unfortunately, a long-term patient of the NHS".
During the touching speech Sir Keir was heckled.
At one point he retaliated saying: "Shouting slogans or changing lives conference."
The Labour leader had been apparently keen to show members and the nation more of himself.
