Laidlaw was a banker, civic worker, and philanthropist. Laidlaw began working for his father's banking firm, Laidlaw & Company. In 1894, he became partner. His father died on January 8, 1902, and the firm continued with the surviving partners, Laidlaw, his brother-in-law Edward Roesler, and his uncle Charles E. Laidlaw. In 1911, Laidlaw became a member of the
New York Board of Trade. In 1919, he was one of 300 delegates who attended a meeting to discuss industry relations and develop plans to address existing issues. The delegates represented 82 community councils of national defense. He was a member of the Bankers of America, Metropolitan Stock Exchange, and the
New York Chamber of Commerce. Laidlaw was also president of the national Men's League. Laidlaw led the proceedings of the men's night of the 4th annual
National American Woman Suffrage Association (NAWSA). Several members of the national men's league, with 23,000 members, spoke to the political and economic reasons why women should have the right to vote. Specifically, as women obtained secondary education entered the workforce, it does not make sense that women would not have the right to provide input on issues related to their fields or trades. In 1911 and 1914, Laidlaw and his wife when on two speaking tours to promote women's suffrage in the western states. Women won the right to vote on November 6, 1917. In a speech after the amendment was passed, Laidlaw said, "The women did it. But not by any heroic action, but by hard, steady grinding and good organization. We men too have learned something, we who were auxiliaries to the great women's suffrage party. We have learned to be auxiliaries." Two suffrage memorial tablets were installed at the New York state and United States capitals. His was the only man's name that was placed on the tablet. ==Personal life==