Now, pay attention for a short history lesson...
PGHS moved to a new building at this site in 1971, having moved from the Southfield Avenue site just along the A761. The Southfield Avenue school was then occupied by St Stephens High School as an annexe to the main school building at the two miles distant Highholm Avenue.
The original PGHS building at Highholm is also being demolished
NS3174 : Highholm School demolition, it was passed to St Stephens when PGHS moved to the new Southfield Avenue building in the late 1950s.
Both schools (one RC and one non-denominational) will share a site here at Kilmacolm Road, along with two special needs schools to form what is being described as a "super campus". Both High Schools currently occupy the Southfield Avenue site while the new campus is being built.
Now, did you follow all that?