page . Editing help is available. For people named Johnstone, see Johnstone (surname) . Johnstone Johnstone shown within Scotland Population 16,847 [1] OS grid reference NS434436 Council area Renfrewshire Lieutenancy area Renfrewshire Constituent country Scotland Sovereign state United Kingdom Post town JOHNSTONE Postcode district PA5 Dialling code 01505 Police Strathclyde Fire Strathclyde Ambulance Scottish European Parliament Scotland UK Parliament Paisley and