Prime Minister Mark Carney speaks to reporters on Parliament Hill on Aug. 18. His adviser Tom Pitfield shares principal-secretary duties with former cabinet minister David Lametti in the PMO.

Tom Pitfield, a top lieutenant to Prime Minister Mark Carney and long-time Liberal Party campaign strategist, is one of the largest shareholders in a marketing and analytics company that has for years been working on behalf of Big Tobacco in Canada and globally, two sources say.

The sources told The Globe and Mail that Mr. Pitfield, who shares principal-secretary duties with former cabinet minister David Lametti in the Prime Minister’s Office, stands to benefit financially from a potential sale of Montreal-based Data Sciences, which he founded in 2014 and whose major client is Philip Morris Intern

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