The complaint by Sue and Bill Gutteridge follows concern about the shorter school day for pupils with special needs.

The Gutteridges complained to Michael Doig, the school’s head, that they learnt of the delay in their daughter Anne’s return only after the start of the summer holidays. “We can only assume that you deliberately did not (let parents know) in an attempt to present us with a fait accompli and avoid a possibly difficult confrontation.”

They said that if Anne had been embarking on Higher courses, as she would if she were a mainstream pupil, she would not have been told to stay at home. How did depriving some pupils of education “accord with North Lanarkshire’s ‘Raising Achievement for All’ strategy which is supposedly concerned with ensuring genuine equality of opportunity?” Ray Murphy, a North Lanarkshire education officer, said staff at the Cumbernauld communication disorder unit would be attending a course on therapeutic crisis intervention, which had been finalised only in mid-June. Achieving the council’s aims of high quality education included giving staff access to appropriate in-service opportunities.

But the Gutteridges replied: “Is it really too much to ask that if teachers want to undertake extra training, they use some of their 65 leave days to do so?”

Paul Dumbleton, chair of Glencryan school board in Cumbernauld, argued in the TES Scotland in June that pupils at special schools were discriminated against by having shorter days. Special schools were the best option for many children, “but at the price of 1,500 lost hours of teaching time” during school life, Mr Dumbleton said.

The Glencryan board has now proposed that North Lanarkshire pilot a longer day for senior pupils. The council has refused, partly because many children have lengthy travel times to school.

The school board will decide on its next step after the holidays but does not rule out legal action.