The civil rights movement, perhaps? Or the sixties and a whole new generation might have had something to do with it.
That would help explain why the unfair treatment of Catholic students, which was tolerated in the 1950s and most of the 1960s, became an issue by 1969, continuing through to 1981:
In May 1969, the OSSTA presented to Premier John Robarts and Davis, his Minister of Education, and later that day to the caucuses of the NDP and the Liberal Party, the brief Equal Opportunity for Continuous Education in the Separate Schools of Ontario. The Association's position was summed up in a statement near the opening of the brief:The purpose of this brief is to obtain for separate public schools of Ontario that equality which is basic to the educational policy of the province, which is demanded by official promotion of continuous child-centred education, and which is implied in the modem reorganization of the school system. This request seeks the removal of the pedagogical and financial shackles which restrain the separate schools from offering a complete educational service from kindergarten to grade 12(13) at the present time.
There was reason for optimism. The Liberal caucus supported the brief, provided that sharing of facilities would take place between public and separate boards. Elie Martel (MPP, NDP, Sudbury East), a former separate school principal, and John Rodriguez, a former provincial president of the Ontario English Catholic Teachers' Association (OECTA), piloted a similar resolution through the NDP convention. . .
In total about twenty high schools sent students to Queen's Park between 21 April and 28 May in 1981. Each group met with its local MPP and stood with placards in front of the parliament buildings while the members of parliament were going to and from lunch. Pictures then went to the local newspapers. The plan worked well enough to create the impression in Dr. Stephenson's mind that the students were at Queen's Park all the time. The following year the "Equality Express" expanded its operation to other centres where the students presented the case for completion.
In 1984 the OECTA met with and received a favourable response from the two opposition leaders in the Ontario legislature, David Peterson and Bob Rae. Shortly thereafter there was an interchange in the House on why Catholic high schools were not being funded. That same year the NDP reaffirmed its support for separate school extension in its Report of the Task Force on Educational Policy. Also that year the OECTA intensified its campaign. . .
In many Catholic boards, the schools did not have senior grades at all - they automatically streamed into the public system after grade 10.
As the above article quotes, there were a range of positions in different counties.
private Catholic schools had closed in only nine communities, but in four of them the separate school board had kept operating grades nine and ten. Hamilton, Toronto, and other places not only kept their Catholic high schools operating, but opened new ones. When Davis turned down the OSSTA' s "Equality" brief, Bishop Emmett Carter of London telephoned Archbishop Philip Pocock to ask his intentions. Pocock stated that he was going ahead with the opening of new high schools, possibly at the rate of one new one per year to meet pent-up demand in Metropolitan Toronto. He believed that such expansion would ultimately convince Premier Davis not only that separate boards would not confine themselves to a grade-eight limit, but also that separate school completion was just and logical. In 1971 there were twenty-three separate boards cooperating closely with Catholic high school boards in the administration of fifty-seven Catholic high schools; these stayed open. Between 1971 and 1984 forty-one new ones were established: twenty-five offering grades nine to thirteen and sixteen offering grades nine and ten. In addition, enrolments in many of the pre-1971 high schools increased. These statistics would impress Davis and would be one of the factors causing him to change government policy with regard to the separate schools.
