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.

[4] 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.

[11] In July 1918, Johnstone was awarded the OBE for services to the Scottish War Aims Committee in the King's Birthday Honours list.

It was founded following revolutionary activities in Russia, French army mutinies and a series of labour strikes in Britain in May 1917.