A World War Two veteran who grew up in poverty and described himself as the "world's oldest rebel" has died.
The son of RAF veteran and author Harry Leslie Smith tweeted to say his father had died while visiting him in Canada.
The 95-year-old Barnsley-born campaigner and left-wing activist suffered suspected pneumonia while with his son John in Ontario.
John said: "At 3.39 this morning, my dad Harry Leslie Smith died. I am an orphan."
Mr Smith divided his time between Yorkshire and Canada and spent time meeting with refugees from around the world and advocating on their behalf.
He rose to prominence after giving an impassioned speech about his life and the NHS at the Labour Party conference in 2014.
After a speech which moved some delegates to tears, he was greeted with a standing ovation and widely praised on social media after warning the UK must "be vigilant" about the NHS.
The son of a miner, Mr Smith lived through the Great Depression and joined the RAF in 1941, serving in World War Two.
After retiring, he became a prominent campaigner against austerity measures with his own podcast and Twitter account with more than 230,000 followers.
Mr Smith developed pneumonia after a fall during the visit to his son.
He was taken to hospital for treatment last week, with John tweeting updates on his father's condition, prompting many messages of support.
After his father died, John tweeted: "It is 4.36 in the morning and I am wrapped in the blanket that covered him as he lay dying. And I know exactly what my steps are. I will follow in his footsteps. I will endeavour to finish his projects."
Labour leader Jeremy Corbyn described Mr Smith as "one of the giants whose shoulders we stand on".
We will all miss Harry Leslie Smith - he was one of the giants whose shoulders we stand on.— Jeremy Corbyn (@jeremycorbyn) November 28, 2018
A World War Two veteran who dedicated his life to fighting for our National Health Service, a peaceful world and for countries to meet their moral responsibility by welcoming refugees. pic.twitter.com/1RW63dSa6Y
Labour deputy leader Tom Watson said "the world is a far better place for his life".
Harry Leslie Smith will remain an inspiration to all in the Labour movement engaged in the fight for justice and fairness. The world is a far better place for his life, words and deeds; and a far sadder place with his loss. Farewell @Harryslaststand https://t.co/B5S6vRG32A— Tom Watson (@tom_watson) November 28, 2018
Former Labour leader Ed Miliband tweeted: "Very sad to hear of the death of Harry Leslie Smith.
Very sad to hear of the death of Harry Leslie Smith. He was one of a kind who never wavered in his fight for equality and justice. We should all carry his passion, optimism and spirit forward.— Ed Miliband (@Ed_Miliband) November 28, 2018
Mr Smith's publisher, Icon Books, said the "world was poorer without him".
We're heartbroken to hear of Harry Leslie Smith's passing. He was a brilliant polemicist and author, an inspiring activist, a loving father, and much more. Icon were incredibly proud to publish two of his books. The world is far poorer without him. #IStandWithHarry pic.twitter.com/VHhyutEwUE— Icon Books (@iconbooks) November 28, 2018
Singer and song writer Billy Bragg called Mr Smith "an inspiration".
Sorry for your loss John. Your father was an inspiration. As the last of them pass away, we all have to commit ourselves to follow in the footsteps of the generation that fought fascism and founded the welfare state. Rest in peace, Harry. @Harryslaststand https://t.co/4N6oz5N9U6— Billy Bragg (@billybragg) November 28, 2018
In recent years Mr Smith visited Halifax, including the town's Borough Market where he was doing his shift at Grosvenor's stall in the arcade when Britain entered World War Two in September 1939.
Leader of Calderdale Council Tim Swift said he would be looking into the possibility of putting up a blue plaque to Mr Smith.
He said: "Harry was a remarkable man who campaigned for his beliefs with astonishing energy in the later years of his life."