Morel was ahead of his time: he campaigned for human rights and was against government secrecy.
He famously defeated Winston Churchill to claim his Dundee seat. But his anti-war convictions saw him sentenced to six months in prison in 1917 under the Defence of the Realm Act.
Although much forgotten since his death in 1925, in a new biography, The Politics of Dissent, Morel is depicted as a brave, campaigning humanitarian.
Author Donald Mitchell says of Morel: "His pursuit of social justice and human rights, his trenchant critique of the establishment and his extraordinarily prolific output made him both loved and hated by his contemporaries."
Morel directed what the biographer calls "the first great human rights movement of the 20th century", which brought King Leopold II of Belgium's genocidal regime in the Congo to an end.
In 1924, Ramsay MacDonald, 11 Cabinet ministers and 125 MPs nominated him for the Nobel Peace Prize, citing his work over the Congo and his efforts to secure a lasting peace. He died, aged just 51, before the winner was announced.
Morel was born Georges Edouard Pierre Achille Morel de Ville in Paris in 1873, to an English mother and French father. Aged eight his widowed mother sent him to England to be educated.
At the dawn of the 20th century, appalled by cruelties in the Congo, Morel began a long campaign to raise awareness in Britain.
In 1904 he established the Congo Reform Association, "which after a decade of remarkable campaigning saw control of the country pass from King Leopold ... and subsequently to reforms".
At the outbreak of the Great War in 1914, Morel became secretary, and prime mover, in the anti-war Union for Democratic Control, seeking parliamentary oversight of foreign policy and a moderate peace settlement.
But his approach put him at odds with the government and, as patriotic fervour rose during the war, he became isolated, and was even physically attacked.
His reputation was further damaged when his friend, the Irish Republican Roger Casement, was hanged for treason for his role in the 1916 Easter Rising in Dublin.
His pacifism led Morel to be sentenced to six months in Pentonville Prison, which did nothing to quell his campaigning, though it damaged his health badly.
Mitchell adds: "[Morel's] concerns are highly relevant to today's global dilemmas, for his work has a direct bearing on many of the critical issues of our times."