When Kelly's disease was diagnosed two years ago, the non-smoker became a crusader for medicinal cannabis as an alternative to conventional treatment. She was in considerable pain, and suffered a broken back from her tumours.
In her case, she also had chemotherapy, but remarked that cannabis was the only drug which eased the pain in her hips and spine and meant she got a good night's sleep.
Typically she spoke bravely about her illness and impending fate. "I'm living, not dying," she insisted last year, though her diagnosis showed her cancer had spread to her brain.
It was a mark of the deep respect she had earned that her passing drew sincere tributes yesterday from across the political and industrial spectrum.
Her colleagues and her critics acknowledged her integrity, tenacity, perception and fearlessness. The Prime Minister, John Key, called her a strong advocate for workers' rights. Helen Clark, his predecessor, said Kelly had fought for others while gravely ill herself.
Business NZ observed that Kelly made a significant contribution to public life, and Federated Farmers acknowledged that she brought rational and empathetic arguments to industrial disputes which were often hard to disagree with.
Kelly inherited her industrial DNA from her parents. Her father Pat was an old-school unionist who left the Communist Party to lead Labour's industrial wing. Her mother Cath organised anti-Vietnam war protests.
The Kelly house in Wellington hummed with activism and ideology. Her parents encouraged her to stand up for what she believed in. After training as a teacher, Kelly got involved with union issues in the education sector before shifting to a wider industrial landscape.
She became the Council of Trade Unions' first woman president in 2007, and led the organisation for eight years.
She trained her fire on farmers, foresters, miners and famously, the filmmaker Sir Peter Jackson, in the dispute over a special deal for Warner Brothers during the making of The Hobbit.
The fact that forests are safer workplaces today than they were a decade ago is due in no small part to a campaign which relied on Kelly's energy and steely determination.
Even as her health deteriorated, she remained on the Pike River case, and saw failure when others saw futility. She was harshly critical of the mine management saying: "We've got to be more mature about who we honour, how we think about things, what we demand."
Helen Kelly was a fine New Zealander, who fought passionately on behalf of others who did not always have the weapons to take into battle. Her great legacy is that she inspired others to carry on the causes she advanced in the interests of a better society.
