It was rainy in Ottawa on the Thursday evening of Sept. 23, 2010, a moody night in the moody season of a newly arrived autumn. At the St. Elias Centre, in the comfortable suburbs of the riding of Ottawa South, local and national Liberal royalty — the venerable Herb Gray, federal hope du jour Michael Ignatieff, former deputy prime minister John Manley, erstwhile MPP and soon-to-be mayor Jim Watson — arrived along with the anonymous party foot soldiers on whose legwork the business of politics runs.

All were on hand — McGuinty family members dotted through the crowd like raisins in a Christmas cake — to celebrate the 20th anniversary of Premier Dalton McGuinty’s election to the Ontario legislature, to toast the nice guy who’d finished first, the local boy who’d made good.

It was the same hall in which the tall, impeccably postured lawyer had announced his 1996 campaign to lead the Ontario Liberals. On tables and easels along one wall were old news clippings, the buttons and bumph of campaigns past, photo albums chronicling one of the most unlikely success stories in Ontario’s political history.

Dalton James Patrick McGuinty, Jr., was an accidental premier, a man seemingly without natural attributes for politics, but the squeaky-clean owner of an otherworldly self-discipline, persistence and capacity for improvement. Save for biological imperatives, an acquaintance joked that night, it was easy to have pictured him wearing a clerical collar as a popular young parish priest in his neighbourhood of Alta Vista.

Elected in 1990, after the sudden death of his MPP father, McGuinty put in six years of famously anonymous service in opposition at Queen’s Park. He shocked his own Liberal colleagues with an audacious run for the party leadership in 1996. Then, just popular enough to be a grudging compromise candidate, he won the job on the fifth ballot of a comically bizarre convention at which, of the six serious candidates, he stood fourth on the first two ballots.

Even to some Liberals, it seemed a perverse mistake, the latest miscalculation of a party that seldom blew the chance to miss an opportunity. But the most consistently under-estimated politician in Canada would have the final chuckle on his legion of doubters, recovering from an initial campaign defeat in 1999 to win the premier’s job in 2003 and 2007 with back-to-back majorities — the first Ontario Liberal leader in more than half a century to do so.

In office, McGuinty evolved into an assured leader of unshakeable composure, a calm he maintained even as Ontario endured wrenching economic transformation, the near-death experience of the auto industry, and humiliating descent into have-not status in Confederation. Through it all, none who worked with him can recall the leader losing his temper or so much as raising his voice.

That night in Ottawa in 2010, the guest of honour, still remarkably fit at 55 and only modestly greyed by the cares of high office, told his longest-standing supporters that while the corrosive nature of politics tends to strip away idealism, he’d never lost his.

Still, for all the goodwill of the evening, the satisfaction of past triumphs and shared memories, a nagging thought might have troubled the minds of the savvier politicos in the hall.

What the fall of 2010 also marked was the closing of a window, the last sure opening gone for Dalton McGuinty to make a graceful exit from Ontario politics, to walk into the history books as near to the top of his game as unforgiving political reality allows.

McGuinty was once asked, when former premier Mike Harris announced his resignation in October 2001, whether his adversary had left too early or too late. Harris had done it just right, he said.

You have to give the party about two years to elect a replacement and let the successor establish a presence. Already, McGuinty was too late for that. Campaigning would begin in less than a year for the election of Oct. 6, 2011. He had, that summer, discussed retirement with his wife, Terri. He discussed everything her. When not together, the two talked regularly on the phone. Politics and the public spotlight had never been her choice for their marriage. But the premier found that as hard as the province's top job was to get, "it was harder to get out."

He decided the most contentious initiatives his government had undertaken in its tumultuous second mandate when Ontario’s economy reeled — massive sales tax reform, the high-risk pursuit of a stake in the green economy — were his to answer for. So he would, as promised, lead a fourth campaign, even though polls suggested this battle would be steeply uphill. That rainy Ottawa evening he told supporters to "get ready for the next election."

In it, he would win a remarkable third government, albeit this one a minority. But McGuinty’s headiest accomplishments were already past, his disorderly finale on the horizon, his legacy soon to be stamped with question marks.

For a year, the premier struggled with the frustrating new imperatives of minority parliament. He became increasingly isolated, surrounded by an inner circle with little political experience, influenced by advisers of more rightward tilt. He adopted an austerity agenda, but in such a ham-fisted manner he made enemies of essential old allies such as teachers and public-service unions. He violated the old Brian Mulroney maxim of always dancing "with the one what brung ya."

On Oct. 15, 2012, mired in accumulating scandal and evidently chagrined at the personal toll exacted on the gentlemanly minister obliged to carry the can for his government’s cynical gas-plant manipulations, the 24th premier of Ontario announced his resignation.

It was a departure quite as shocking as the 1996 victory that had brought him to Liberal leadership. For on his way out the door, Dalton McGuinty, the premier who boasted that he never lost his idealism, the man who said his own mother's advice to him on his wedding day was that "whatever happens, keep talking," shuttered the Ontario Legislature indefinitely through prorogation.

It left his own party to deal with the shambles of an exit to which, tellingly, no member of his cabinet or caucus had been privy. It left Ontario Liberals to choose a successor, prepare a spring budget, and gird for the 2013 election almost certain to follow — a contest in which their survival was in jeopardy. And it left Ontarians, once again, baffled by the over-achieving enigma from Ottawa South.

"Leadership can't always be about being popular,"" Premier Dalton McGuinty had said that happy night two years earlier in St. Elias Hall, before the unravelling began.

And the manner of his exit could hardly have made him less so.