Born in Vancouver,[1] Johnston grew up in the neighbourhood of Fraserview and graduated from Killarney Secondary School in 1968.[2] He attended the University of British Columbia, and earned his Certified General Accountant designation in 1976; he subsequently worked as a public practice accountant before moving into private business in 1980.[2] He became a director of Richmond Savings Credit Union in 1986, and he served as board chair from 1995 to 1998.[1][2] After Richmond Savings was merged into Coast Capital Savings, Johnston also served on the board of that institution.[2] He was also president of Richmond-based transportation company Novex Delivery Solutions.[3]
He was replaced as the Liberal candidate in Vancouver-Fraserview for the 2005 provincial election by Wally Oppal, who was recruited by party leader Gordon Campbell to run in the riding.[6][7] After finishing his term as MLA, he ran in the 2008 municipal election as part of Richmond First, and returned to Richmond City Council.[8] He was re-elected councillor in 2011 as a Richmond First candidate,[8] then in 2014 as part of the Richmond Community Coalition;[9] he lost re-election in 2018 by finishing in 12th place.[10][11]
He married his wife Diane in 1972; they have two children together.[1][2]