For the past four years, the Canadian government has lacked a No. 2.

Because in Ottawa, it is Prime Minister Stephen Harper who runs the show.

While he has many recognizable and loyal lieutenants, the 51-year-old Harper has never identified a deputy leader, the way his six immediate predecessors did.

It's always been an informal title, one that does not carry any extra pay or specific responsibility. But the deputy prime minister is a rare designation that has only been given to nine people in Canadian history -- six Liberals and three Progressive Conservatives.

According to the Parliamentary website, it was Pierre Trudeau who first introduced the deputy prime minister to the lexicon of Canadian politics in September 1977.

Trudeau then named Allan MacEachen, the veteran Nova Scotia Liberal as his deputy, while he also served as his Government House leader.

Nelson Wiseman, an associate professor at the University of Toronto, recalls MacEachen being a wise choice for Trudeau's second-in-command.

MacEachen would later do much of "the wheeling and dealing" that led to the defeat of the short-lived government of Conservative prime minister Joe Clark, Wiseman said in a recent telephone interview with

In fact, MacEachen was sitting shotgun the day Trudeau defeated Clark, the youngest-ever prime minister, in December 1979.

"All eyes were sizing up Mr. Trudeau, then the Leader of the Her Majesty's Loyal Opposition. I was his desk-mate," MacEachen later recalled in "Pierre," a collection of essays about Trudeau that was edited by journalist Nancy Southam.

Within three months of the Clark defeat, Trudeau was back as prime minister and MacEachen was given back his prior honorary title.

Clark, on the other hand, never appointed a deputy during his nine months in office.

Aside from Harper, Clark is the only prime minister to go without a backup in the past 33 years. Even Kim Campbell had a deputy -- Jean Charest, the current premier of Quebec -- during her tumultuous four months at 24 Sussex Drive. So did John Turner, who picked a future Canadian leader, Jean Chretien, to serve in this role during his own three-month stint as prime minister.

Wiseman said the deputy leaders that have emerged since MacEachen's time have had different degrees of influence within the government, reflecting the informal nature of the position.

"Even when you do have the job, the parameters are carefully determined by the prime minister," he told

Wiseman points to Don Mazankowski, who served as second-in-command for nearly seven years under prime minister Brian Mulroney, as one of the most powerful deputy ministers ever.

Mulroney's first deputy prime minister was Erik Nielsen, a Clark loyalist whose style clashed with the new Conservative leader's own.

Just over two years into Mulroney's first mandate, Mazankowski was the new No. 2.

According to Mulroney's memoirs, he told his cabinet that Mazankowski's role as deputy prime minister would be best to act as the "chief operating officer of the government."

He told cabinet members that Mazankowski "has my full confidence and absolute trust," as an individual who had the authority for the government.

But in the end, it's the prime minister's call as to what precisely the position entails.

During the Chretien years, three people were given the deputy prime minister title: Sheila Copps, Herb Gray and John Manley.

Copps remembers the "three little words" on her business cards that made her the brunt of criticism that suggested her title was largely for show, when she became the first female deputy prime minister.

"One of the first articles on my appointment set out to show that I wasn't really a deputy prime minister, I was just a skirt put there to fulfill gender expectations," Copps wrote in her memoirs "Worth Fighting For."

The last deputy prime minister was Anne McLellan, who held the title under the minority government led by Paul Martin.

She lost her title when she lost her seat in Parliament and Martin was defeated in the 2006 election that made Harper prime minister.

Today, the official word from the Prime Minister's Office is that Harper has "no particular reason" for not naming a deputy.

"It's an honourary position, not a formal one," PMO spokesperson Andrew MacDougall told in an email.

Author William Johnson, who wrote a book about Harper's rise to power, sees the deputy prime minister title as being ceremonial and inconsequential.

While Johnson describes Harper as a "control freak, especially with regard to communications," he does not think the prime minister's decision to go without a deputy is noteworthy.

Instead, Johnson says it is much more significant that Harper has not named a formal Quebec lieutenant, which has traditionally been a key power position in ruling parties.

Wiseman said Harper's decision to go it alone is "completely consistent" with his style of managing the government.