Johnstone co-founded the Loose Moose Theatre, and invented his system of training that has been influencing practice within and beyond the traditional theatre for over 50 years.
Johnstone kaasasutas Loose Moose Theatre'i, ja lõi oma treeningsüsteemi, mis on mõjutanud traditsioonilise teatri praktiseerimist enam kui 50 aastat.