My friend and mentor John Morton, who has died aged 83, devoted his life to music, the theatre and friends. Throughout the 1960s and 70s, John worked as a freelance director for Opera North, and took charge of musicals for various amateur and semi-professional companies in the north-east of England. He also played a large part in reviving the fortunes of the Darlington Civic theatre, and was a driving force behind the restoration of the Georgian Theatre Royal in Richmond, North Yorkshire.

He made his living through a combination of freelance directing, a little teaching, set and costume designing and consultancy work in the musical field. He also performed one- and two-handers in the manner of Flanders and Swann with other musicians and actor friends.

John was the only son of Jenny and Sidney. His early childhood was spent in the village of Reeth, North Yorkshire, and he then attended the Queen Elizabeth grammar school in Darlington. After training as an actor in the 40s and touring in repertory theatre, he studied the ondes martenot – a kind of early, eerie-sounding electronic keyboard – under Jeanne Loriod in Paris, and returned to Darlington with a beautiful instrument of his own, built for him by the Martenot brothers.

On this he took part in two performances of Olivier Messiaen’s masterpiece, the Turangalîla Symphony, at the BBC Proms in the 1970s, and on film scores for Elmer Bernstein. He appeared with the London Symphony Orchestra, their conductor Andre Previn, Mia Farrow and Michael Gambon in a performance of Arthur Honegger’s Joan of Arc at the Stake at the Royal Albert Hall in 1971, and even turned up on Blue Peter with his ondes martenot.

I was a sixth-former in Darlington in the late 60s when I won a place on a local drama summer school on which John was a tutor. During a lunch break he spotted me copying designs from a Biba catalogue in thick black ink strokes, and declared – entirely without fake enthusiasm or intention to patronise – that I had “immense talent”.

Over the next few years I was a regular visitor to the music-and-parlour-games salon that he and his eccentric mother held at their bohemian and rather grand apartment in what to me was otherwise a dark and drizzly northern town. He utterly adored his mother, and lived in Darlington with her until her death in the early 80s.

An accident more than 20 years ago put paid to most of John’s working activity. He made a significant contribution to the cultural life of a very large number of people, and was extremely good company.