If you've worked on an election campaign, you know the last days are do-or-die. You watch the overnight polling, and when a candidate is losing, more often than not, the gloves come off.

In the last ten days of Election 42, Stephen Harper started saying that Justin Trudeau would cancel a popular tax-saving program for seniors. Trudeau was correcting the misinformation on the campaign trail but, according to CARP, 25% of seniors today live in poverty. The mere possibility of more financial stress left pensioners confused and frightened.

Seniors are almost twice as likely to vote as young voters, so this lie could be lethal for the Liberals. When the Conservatives turned the lie into TV and radio ads, and ran them in heavy rotation, the party knew it had to act quickly, and break through with clarity and conviction. After all, our ad had to be more believable than the Right Honourable Prime Minister Stephen Harper.

Lying to seniors is a terrible thing to do, but frightening them, knowing that they're vulnerable, is worse. Working with Bensimon Byrne, the party decided to expose not just the lie, but the manipulation, likening it to the phone scams seniors get. In those final days, battling for attention with all other campaign advertising and the Blue Jays playoffs, the ad had to break through. The agency decided to use humour – a strategy effective in other categories and rarely used in political campaigns.

The agency got the urgent brief nine days before the election, at 6:30am. It had an approved script by 8:30am. Who better to set the record straight than 94-year old Hazel McCallion, former Mayor of Mississauga? Who better than "Hurricane Hazel" to expose tactics intended to scare and confuse seniors?

Bensimon worked with Hazel and her team over the weekend to bring her on board and find time in her busy schedule. She agreed and gave the team 27 minutes to shoot! With her steely eyes, looking to camera, she spoke for all of Canada's seniors saying, "Do I look scared to you, Stephen." Twenty-four hours later the ad was edited, on TV and released online – just five days before the election.

The ad was the top trending Facebook video for the next two days, gaining over four million social media views, all unpaid. It turned around the seniors' vote, from Harper to Trudeau, with a massive 19-point swing in vote intention in the critical last days before Canadians entered the voter's box.

Trudeau won a 184-seat majority, from a distant third place, for the first time in Canadian political history. Liberals achieved a 150-seat gain, the largest-ever, from an ingoing 34 seats and also doubled their share of the popular vote, from 18.9% in 2011, to 39.5% (another first). One journalist asked rhetorically if Hazel's endorsement actually won Trudeau the election.