Keir Hardie is Labour's greatest pioneer and its greatest hero. Without him, the party would never have existed. Without him, Attlee, Bevan and Castle would never have become cabinet ministers. This extraordinary man rose from the pits of Ayrshire to change the world. He became the first Labour MP, the founder of the ILP, first leader of the Labour party, pioneer editor of the Labour Leader, and a giant in the socialist movement worldwide. Miraculously, he created a new party, as "an uprising of the working class".

Hardie was both our greatest strategist and our greatest prophet and evangelist. His vision made the Labour Alliance. He saw that a mass party needed a mass working-class base, the unions from which he himself had sprung. But his ILP also brought in middle-class socialists. Labour should "blend the classes into one human family", but always, independently, "work out its own emancipation".

And he was a unique popular crusader. In Cambridge in 1907 the young Hugh Dalton was deeply moved by Hardie's "total lack of fear or anger"; he became a socialist that night. No one more powerfully exposed the cruelties of late-Victorian capitalists like Lord Overtoun's "white slavery". Yet Hardie insisted that socialism "made war upon a system not a class". Labour should "capture power, not destroy it".

Hardie attached his party to great issues and values still relevant today. He was the greatest-ever male feminist. Through his friendship with Sylvia Pankhurst, he insisted that women's liberation involved women not just as voters, but as mothers, workers, human beings. He crusaded passionately against poverty: his proud description was "member for the unemployed", campaigning for the minimum wage and eliminating child poverty. He pioneered social welfare, advocating a national health service financed from redistributive taxation, not a poll tax. He was a principled democrat. His socialism was not a massive state bureaucracy but the true republican democracy of Milton, including Welsh and Scottish devolution. His global vision linked Labour with colonial freedom. In Bengal in 1907 he outraged the Raj by demanding that India should actually be governed by Indians. I once saw a walking stick in Hardie's Cumnock home, a present from his great admirer, Mahatma Gandhi. In South Africa, Hardie almost uniquely argued that self-government there was for whites only and that in Natal and Cape Colony black Africans' status would seriously erode. And finally, Hardie anchored Britain in the international socialist movement. He was, like Wordsworth in 1789, a citizen of the world. He crusaded with French comrades for international peace. He stood up courageously during the Boer war, denouncing its "methods of barbarism". In 1914, he was horrified by that imperialist bloodbath, and it killed him. As George Bernard Shaw movingly wrote, Hardie's indomitable truth would still go marching on.

Hardie's greatness is reflected in the simplicity of his lifestyle. You could never imagine him, like Attlee, counting up the number of Etonians in his government nor, like Bevan, quaffing Bollinger with Beaverbrook. Bruce Glasier wrote of Hardie that "the man and his gospel were indivisible". His simple heroism made our party and our world.