Johnstone also had parliamentary ambitions and was adopted as Liberal candidate for the constituency of
East Renfrewshire. Reflecting his interest in promoting effective business activity, he successfully moved a resolution encouraging the creation of
joint industrial councils as a means of promoting cooperation between capital and labour and avoiding industrial strife, at a conference of the Council of the Scottish Liberal Association in Glasgow in November 1918. In
1918 Johnstone was elected as
Coalition Liberal MP for Renfrewshire East in a straight fight with the
Labour candidate
Robert Spence. The seat had been
Conservative held at the two previous general elections of
January and
December 1910 but the Tories did not oppose Johnstone in 1918, presumably indicating that he had received the
Coalition Coupon. But Johnstone, while one of those Liberals who supported
Lloyd George and the need for a strong government to prosecute the war, criticised the use of the coupon and looked forward to Liberal reunion. After the war ended, Johnstone said that he would be one of a number of Liberals elected in 1918 as supporters of the Coalition who would stand at the next general election as Liberals ‘without prefix or suffix’. Notwithstanding this, he was still sufficiently closely associated with Lloyd George that when the
1922 general election came Johnstone was first shown in the national press as a
National Liberal. By the time nominations were declared however, his description had changed to straightforward Liberal. In 1922 Johnstone was opposed by both Labour and Conservative opponents and came third behind both the successful Labour man Robert Nichol and the Tory, Sir Frederick Lobnitz, winning just 17.5% of the overall poll. Johnstone did not stand for Parliament again. ==Other appointments==