Only one high school in Dumbarton and the Vale is offering pupils the opportunity to sit eight National 4s and 5s examinations - while all other local authority schools only offer six.

The figures were revealed this week from think tank, Reform Scotland, who believe the “variation across Scotland is placing some pupils at a disadvantage”.

Our Lady and St Patrick's High (OLSP) in Castlehill, decided to retain eight subjects in fourth year, after discussions with parents and staff, before the new examination system came into effect in 2014.

As part of the national education shake up, each local authority area and individual school were allowed to choose the number of subjects pupils would take exams in, ranging from five to eight.

But Reform Scotland claims this decision rather than have a national consensus “leads to a situation where different pupils have different numbers of qualifications based not on ability but on a decision made by their school or local authority”.

All other high schools in West Dunbartonshire – Vale of Leven Academy, Dumbarton Academy, Clydebank High and St Peter the Apostle High School – decided to stick with the council decision to offer six.

However, at OLSP, the Parent Council and former head teacher Charles Rooney worked with West Dunbartonshire Council to host a parent forum to ensure pupil's futures would not be damaged.

Current chair of the Parent Council, Kathleen Owen, told the Reporter it was important everyone worked together to achieve the best outcome.

“The Reform Scotland research completely backs our decision. At the time our head teacher, Charlie Rooney and Billy Myers the chair of the Parent Council along with the staff and parent council board realized young people would be disadvantaged if this model was put in place,” she added.

“It was a very challenging time for everyone but we had to do it, to ensure the young people at OLSP continued to achieve their full potential and we’ve been vindicated."

The “Postcode Lottery” effect, according to newly re-elected MSP Jackie Baillie, is widening the attainment gap and leaving pupils asking why they sit fewer subjects than others.

“As the exam timetable draws to a close this week and pupils head off for their summer holidays, many will be wondering why they sat exams in fewer subjects than some pupils at neighbouring schools. This is happening in schools up and down the country.

“Scottish education used to be the envy of the world but now we have a narrowing curriculum and the attainment gap is widening.

“There is no future for Scotland in building the kind of low-skill, low-wage economy that comes from a failure to invest in education.”

West Dunbartonshire Council said it is focused on supporting all young people to achieve their potential and it will continue to develop curricular models “in partnership with pupils, staff and education services”.

A spokesman said: “Curricular models have been developed in partnership with each of our secondary schools to meet their needs and circumstances, and these are continually reviewed in collaboration with pupils, parents, staff and Educational Services.

"All of our young people have the opportunity to develop skills for learning, life and work and to make choices across S4, S5 and S6 to gain qualifications which reflect their interests and abilities.

"Our focus remains on supporting all of our young people to achieve their potential and move on to a positive, sustained destination that is right for them whether that is further study or employment. Attainment continues to rise across all of our secondary schools and last year’s exam results were our best to date.”