He farmed sheep and cattle in the Raglan area.
[1][2] He won the Raglan electorate in 1946 in the by-election caused by the death of the previous MP, Robert Coulter.
However, he only held the electorate from 5 March to 27 November 1946 as he was defeated by Alan Baxter in the 1946 general election.
[3] In the 1966 New Year Honours, Johnstone was appointed an Officer of the Order of the British Empire for services to farming and in political life.
This article about a New Zealand National Party politician is a stub.