Gardiner was a prominent member of the Progressive Conservative Party of Canada in both federal and provincial politics, organized conventions and developed policy in the 1930s and 1940s.

It was in the third year at Parkdale that Gardiner started to develop his competitiveness, a trait he would use for material gain and political ends later in life.

[4] In 1913, Gardiner entered the University of Toronto, in general arts, transferring in the second year to honours political science.

Gardiner worked hard at his studies and won the political economy department's Alexander Mackenzie Medal in 1916.

[6] While serving in the army, Gardiner developed a lifelong interest in gambling and became proficient at cards and dice.

[7] Because of his service in the war, Gardiner was given an honours degree by the University, and he did not have to finish his fourth year of studies.

He received the Chancellor Van Koughnet scholarship, a $400 cash prize and the Law Society's gold medal.

[8] Gardiner used most of his $400 prize to buy an engagement ring for Audrey Seaman, a railway clerk and daughter of the proprietor of a prosperous flooring company.

Gardiner left the practice in 1921 and joined Commercial Credit Company of Canada, as a legal associate.

Gardiner took criminal cases, litigation and continued to handle legal work with Commercial Credit.

Gardiner also accepted stocks as payment for his legal fees and he amassed investments in a diverse number of companies.

In 1946, his final year as reeve, Gardiner was also Warden of the County of York, a title similar in some respects to his later chairmanship of Metropolitan Toronto.

Gardiner chose not to run because he thought the Conservatives would remain in opposition, and he would "sit in the back row of the Commons and wait for the boss to tell me when to make a speech.

Gardiner was instrumental in the 1942 Port Hope policy conference, chairing the discussions of the labour committee.

[18] Gardiner would continue his work inside the party for the rest of the 1940s and chaired the resolution and policy committee himself at the 1948 federal leadership convention.

Gardiner was even considered to run for the leadership of the Ontario Progressive Conservative Party (and therefore provincial premier) in 1948 but chose to support Leslie Frost instead.

Planning studies anticipated that the townships and villages surrounding Toronto would be the scene of any future growth.

The Frost government approved the idea and passed it in April 1953, naming Gardiner the first chairman of the Metropolitan Council, made up equally of city and suburban representatives.

On weekends, he would tour Metro Toronto public works projects, rapid transit facilities, urban renewal sites and tracts of suburban housing.

He controlled procedural questions strictly, which challenged dissident members to appeal his decisions, which no-one was able to do throughout his term.

Leslie Frost commended his performance in 1956 by that stating that the success of Metro to date "has been very largely dependent upon your own personality.

My diagnosis was that if I was going to get anywhere I had to know more about any given subject than any individual councillor, and more about metropolitan business as than all the members of council combined.

Engineers were interested in studying alternate routes, which Gardiner prevented: "councillors could not afford to stop, look and listen.

At the 1956 inaugural meeting of Metro Council, Gardiner stated that "it is a snare and a delusion to spend millions on expressways in the belief that they alone will solve traffic problems."

He also stated that "the irresistible fact is, you simply cannot provide sufficient highways and parking space to accommodate every person who desires to drive his car downtown."

[36] Metro Toronto greatly expanded the ability to finance capital works projects and Gardiner followed three principles in the allocation of money.

He served as vice-president of the Canadian National Exhibition Gardiner had retired from the Metro Chairmanship because of his ill health, particularly arthritis.

Philip Givens considered Gardiner the "catalyst for it all, the transition that transformed Metro into one of the great cities of the world."

Paul Godfrey considered Gardiner his idol, admiring his ability to "solve political problems and bring people together".

Gardiner's services to the community in the field of politics and other areas of civic welfare were recognized by the University of Toronto, when he was granted the degree of Doctor of Laws honoris causa.