This is the same Bruce Johnstone who was mysteriously offered a drive with BRM in 1962 when in fact no such job existed. He eventually drove in the South African races at the end of the year in the works "hack", with no assistance, and then stayed behind when they returned to Bourne. A year wasted and his bank account empty.
It was all very strange. In his splendid BRM history the best historian on earth Doug Nye couldn't really understand it all. See Volume 2, P.180 for a full page about Johnstone.