The left-wing New Democratic Party of Canada has long had a favourite rally chant: “Liberal, Tory, same old story”. After Monday, it will have to put that one on the shelf for a while.

The big news in Canada is the election of incumbent Conservative Prime Minister Stephen Harper to his first majority government. The far more fascinating story is what happened in the rest of the field.

The Liberal Party — the supposed natural governing party — was halved to a rump of 34 seats. The French separatist Bloc Quebecois was reduced from 47 seats to four. And the New Democratic Party, which has never won more than 43 seats, surged to 102 seats. The NDP’s Jack Layton will become the first leader of Her Majesty’s Official Opposition in more than half a century of his party’s history.

Imagine a fusion of Labour Left and the Greens winning 30% of the primary vote a third of the seats in Parliament and you start to come close to how startling this result is. Yet almost as surprising was how it happened.

Six weeks ago, Canadians were getting ready to ignore what looked like the most interminable election in recent memory. The only real question was whether Prime Minister Harper could eke out the 12 seats he needed to form a majority.

Then something happened. Perhaps it was Layton attacking Liberal leader Michael Ignatieff on his non-attendance in Parliament during the English-language debate, or in the French, his warm accommodation of Quebec nationalism within modern Canada. Maybe Layton — or Jack, as Canadians know him — came into his own in his fourth election campaign, combining tough opposition to the Conservatives with his earnest optimism and charisma. Perhaps it was simply that those years of dedicated work from activists and organisers in Quebec finally reached a tipping point.

The New Democrats surged to the front in Quebec and, once started, the wave built quickly. Jack’s approval ratings soared and national poll numbers climbed. The solidly progressive platform of the NDP (cap-and-trade, small business initiatives, a roll-back of corporate tax cuts and boosts to pensions, health care and education) gained traction.

On election day, 39.6% of Canadians voted Conservative, 30.6% New Democrat and just 18.9% Liberal.  Ignatieff lost his seat, as did Bloc leader Gilles Duceppe.  The NDP won a stunning 58 of Quebec’s 75 seats, up from just one before the vote.

Canadians decided, resoundingly, to change the game. How that plays out over the next four years will be fascinating to watch. Harper will need to balance his right-wing instincts with the centrist agenda on which he was elected, while Jack and the NDP will need to adjust to new responsibilities and intense scrutiny. Neither will be easy. As for the Liberals, they will have plenty of time to work on some of their own chants.