Perhaps best remembered as a co-creator and writer of the 1970s BBC series Warship, this Scottish author also wrote five novels and penned episodes of the ITV shows The Sandbaggers and Wilde Alliance.
He published his debut crime thriller novel, A Slaying in September, in 1967.
When he began writing Warship, he was serving in the British Royal Navy.
In 1979, he disappeared while flying in a small plane with his girlfriend Susan Insole and his pilot friend Graham Barber. United States Coast Guard officers detected that the plane was in trouble but were never able to locate a crash site or any victims (or survivors -- although all on board are presumed dead).
Actor Donald Burton starred as Commander Mark Nialls in the early seasons of Mackintosh's Warship series.