Dave Ketchum, an actor, writer and director, was also a Timex Sinclair user. If you’ve seen Get Smart in re-runs or have seen the remake, you’ve seen him: he played Agent 13.
In his review of Thomas Woods‘ ZX-Data Finder in issue 3 of Timex Sinclair User, Ketchum alluded to his background in mentioning that his “business is writing television shows (Happy Days, MASH, and others).”
Ketchum gave a thorough review of ZX-Data Finder, pointing out how it was superior to other products and how he used it to keep track of scripts he worked on.
ZX-Data Finder was the predecessor to ZX Pro/File.