Toronto: Friendly old Canada, left for dead after nine years of stern rule under the divisive government of the Conservative prime minister Stephen Harper, has returned with a vengeance after voters overwhelmingly turned to a charismatic Liberal named Trudeau in a bid to recapture the glory days that characterised his father’s long and memorable rule.

“Sunny ways!” a hoarse Justin Trudeau exulted as he accepted his striking victory in Canada’s 42nd general election. “This is what positive politics can do.”

The Liberal party’s resounding victory proved that “a positive, optimistic, hopeful vision of public life isn’t a naive dream”, said Trudeau. “It can be a powerful force for change.”

Once mercilessly derided as “just not ready” for the job in persistent Conservative attacks ads, the former drama teacher performed flawlessly throughout the campaign, demonstrating a true populist ease with voters while his party posted videos of the handsome leader sparring with his shirt off or paddling a canoe on a misty river in the manner of his father, the former Canadian prime minister Pierre Trudeau.

Over the course of a 72-day campaign, Trudeau led his party from last place in the polls to a resounding victory, winning 184 seats in the 338-seat House of Commons, according to unofficial results, and the right to form a majority government.

But by the end of Monday night, Trudeau’s winnings included the heads of both his major rivals, Conservative leader Stephen Harper, and the NDP’s Tom Mulcair. For a campaign that remained relentlessly upbeat and scornful of what Trudeau called “the politics of fear and division”, the result was exceptionally bloody.

The new Canadian leader’s easiest job will be showing the world that Canada has returned to its traditional role of international boy scout, abjuring the hard-right, militaristic and climate-denying record of the Harper government. In that, he will be helped by the fact that the previous government — despite its own rhetoric and that of its enemies — never completely abandoned the role.

Canadians and international observers can expect a sharp change in tone if not policy with respect to refugees and Canada’s involvement in the Middle East. In his victory speech, Trudeau also took pains to disavow the previous government’s attempts to win votes by inspiring fear of Muslim women who cover their faces.

“We know that our enviable, inclusive society didn’t happen by accident, and won’t continue without effort,” he declared.

The substance of the new leader’s claims will quickly be tested on the international stage at next month’s Paris climate summit, where a hastily assembled Canadian delegation will struggle to shake off the country’s reputation as a laggard in the international fight against climate change.