The John Neilson Institution would not have been the school it was had it not been served over the years since its foundation by a succession of gifted and dedicated Headmasters supported by equally devoted members of staff, many of whom, having been former pupils themselves, took more than a merely professional interest in the welfare of the school and of its pupils. It is to these Headmasters and teachers that it owed much of its sense of tradition and its feeling of continuity over the long period of its existance. Nor would this testimonial be complete without making reference to the contribution of the Gardner family. From the very founding of the school when Archibald Gardner inspired and directed its early course, through the time of James Gardner, his son, that of James Gardner, his grandson, and the era of the Renfrewshire Educational Trust, there had always been a Gardner to protect the interest of the school with a wise beneficence.

In 1968 the John Neilson High School moved to a new site in Ferguslie where it remained until 1989 when it was absorbed into Castlehead High School. In 2001 the JNHS buildings in Ferguslie were pulled down, although the JNI 'dome' building in Paisley's West End remains a local landmark.