All I can remember / tell you about Instone is that they were based at STN in the very late 70's early 80's. I was a ground engineer with Transmeridian Air Cargo at the time, and I remember they were locally known as "Flintstone Aviation". This probably was because they were flying two Bristol "Vibrators" (Freighters ) at the time.
Mike.
Just wonder about the year.?
Would that be Freds start up using a couple of ex RNZAF Frighteners?
He was on the Merchantman at ABC late 70's