Kenneth Thomson, the former chairman of Thomson Corp. who became Canada’s richest man by turning a chain of newspapers into one of the world’s biggest distributors of financial data, died yesterday at his office in Toronto of an apparent heart attack. He was 82.

Thomson was chairman of Thomson Corp., the owner of Westlaw legal research and First Call financial data, from 1978 until his retirement in 2002, when his eldest son David succeeded him. He remained on the company’s board and was chairman of Woodbridge Co. Ltd., the family holding company. He was ranked this year by Forbes as the world’s ninth richest man, with a fortune estimated at $19.6 billion.

Thomson’s father, Roy, purchased a rural radio station in the late 1920s.

After serving as an Air Force mechanic in World War II, Kenneth Thomson got his start in the newspaper business in 1947 as a reporter at his father’s first newspaper, the Daily Press in the northern Ontario mining town of Timmins.

Thomson assumed control of the Thomson family business in 1976 when his father died, leaving “Young Ken,” as he was known, with newspapers that included London’s Sunday Times and The Times.

He immediately sold the two British newspapers, which were beset with union problems, to Rupert Murdoch and retreat to Canada. He later moved away from newspapers altogether and into the provision of financial data.

Thomson boosted the value of his business to C$29 billion from about $500 million when he took over in 1976, the Globe and Mail reported today.

Thomson was known for his love of art, and was a collector of works by Cornelius Krieghoff, who painted scenes of Canadian rural life in the 19th century. He donated most of his collection, including Peter Paul Rubens’s masterpiece “The Massacre of the Innocents,” to the Art Gallery of Ontario in Toronto.