The "Experimental" bit of Parkside School, at least in the late 1960s/early 1970s was to do with shipping pupils and some of their staff in from two different Schools, for a fortnight, to mingle and work together on themed projects with the Parkside Staff.
I seem to recall the schools were usually very different social areas, from places like Stockport, Oldham, areas of Manchester and further afield, shipped in by 'bus each day, and each group had a classroom base with at least one member of staff from a School, and one from the Parkside contingent. The Mansion in the Park, and the tower, and indeed the whole area were used as resources.
I seem to recall some small animals kept on site as well, and the classroom buildings formed the four sides of courtyards. Meals were taken in a sort of canteen type room, again, the children were "encouraged" to mingle. On the final day of each "course" parents were invited to attend, and pupils put on exhibitions and playlets, and displays. My memory is that the vast majority of the parents who came to see the work their little dears had done were - predictably - the more middle class ones, sadly.