[3] When Macnaughton announced his retirement as MP for Mount Royal, Smith stepped forward to seek the Liberal Party's nomination to succeed him.
[3] In 1967, Smith left Montreal for Hamilton, Ontario to become associate professor of psychiatry at McMaster University Medical School and run the in-patient unit at St. Joseph’s Hospital.
The Liberals lost one seat in the legislature in the 1977 election, but nonetheless displaced the New Democratic Party as the Official Opposition to William Davis's Progressive Conservatives.
As a politician, Smith had a reputation as an intelligent but dry and somewhat aloof personality, in a province that had grown accustomed to avuncular leaders.
He resigned as leader after the election, and left the legislature in January 1982, a month before the leadership convention that chose David Peterson as his successor.
Peterson said of Smith that: "History will record that he played a major role in the modern success of the Ontario Liberal Party by dragging us into the 20th century and establishing roots in the urban areas.”[5] In January 1982, he began a term as chairman of the Science Council of Canada, a federal government body, which he led until 1987.
[4] A year after leaving the Council, he founded RockCliffe Research and Technology Inc., a firm which introduced public-private partnerships into government laboratories.
PUMC itself was then sold on the basis of an evaluation of approximately $150 million, while the parent company collapsed when it acknowledged that it had significantly overstated earnings from its copper-trading business.
Philip Services stock options became worthless; as these were a significant portion of Smith's remuneration, he failed to receive much benefit from the financial success of his company, PUMC.