A female teacher has won a sex discrimination case after being paid thousands of pounds less than a male colleague.

Pamela McMullan, the head of food and fabric technology at the Royal School Dungannon, in Northern Ireland, was paid less than a male teacher who had fewer responsibilities, an industrial tribunal has found.

Ms McMullan estimated that not being paid the higher management allowance given to Nigel Canning, the head of design and technology, had cost her around Pounds 30,000 in real-terms pay over the past 15 years.

Having now won her case, Ms McMullan, who still works at the school, said she hoped it would be a “landmark for others to follow”.

“I am not a crusader by nature, but felt that the school did not initially take my case seriously or deal with it fairly,” she said.

“I feel passionately that I was treated unfairly and that equality is very important in all walks of life. I’m glad I have seen it through.”

Ms McMullan took her pay complaint to the Royal School’s board of governors in 2006, but it refused to rectify the situation, prompting her to take it to an industrial tribunal.

The tribunal found Ms McMullan was being paid less than three male teachers despite them having broadly similar roles as heads of department. In the case of the heads of biology and modern languages, the tribunal accepted the school’s argument that those teachers were paid more because they were responsible for larger departments and more staff.

But it found that Mr Canning, the head of design and technology, was being paid more than Ms McMullan despite having less responsibility in terms of pupil numbers, staff supervision and the number of lessons taught.

The tribunal rejected the school’s argument that it had been necessary to pay Mr Canning more because of difficulties in recruiting for his post in 2000.

It said the school had failed to prove there was a “genuine material factor untainted by sex” to pay Mr Canning more.

The tribunal noted that the Royal School has 17 heads of department in total, nine of who are women. The highest-paid head of department is also a woman.

Ms McMullan said she has not let the case affect her work with her pupils and other staff.

“I’ve had nothing but the best support from my fellow teachers and fellow heads of department, who have been 100 per cent behind me,” she said.

Eileen Lavery, from the Equality Commission for Northern Ireland, which represented Ms McMullan, said the case underlined “the need for employers to have a fair and transparent pay policy”.

Mark Langhammer, Northern Ireland director of the Association of Teachers and Lecturers, Ms McMullan’s union, said it was “patently unfair” that she had been earning less than a male head of department.

“Schools must have clear and transparent salary policies, and must apply them fairly,” he said.

“If they don’t, we will fight to make sure they change their ways. And teachers should take heart that equal pay cases are winnable. They should not be scared to stand their ground if they are being treated unfairly.”

A decision regarding possible compensation will be made at a later date.

The school refused to comment.