Their victory at the Employment Appeal Tribunal, which is likely to be challenged, substantially increases the chances of other white-collar staff, such as nursery nurses, claiming pay with teachers and blowing apart disparities in local government pay scales.

Linda Marsh, spokeswoman for the authorities, commented: “Directors of education will be studying the decision with a view to appealing to the Court ofSession” The councils claim the differences between teachers’ pay scales, set by the Scottish Joint Negotiating Committee, and other staff on Administrative, Professional, Technical and Clerical conditions will be destroyed if the judgment is upheld in the higher courts. They also argue it would cost millions of pounds to end differentials, making worse the financial crisis which they are facing.

In its written judgment, the appeal tribunal in Edinburgh, chaired by Lord Johnston, dismissed the local authorities’ appeal against the earlier verdict of an industrial tribunal in Glasgow. The authorities submitted seven defences but all were rejected.

In a key passage, Lord Johnston states there was no reason why the instructors should not have been paid the same as teachers when they were doing the same job. Instructors should have been regraded and there was “no logic” in the councils’ arguments that success for the instructors would mean the dismantling of the APTC scales.

“The issue is one of equal pay for like work,” he says.

Lord Johnston contends that the local authorities had not shown any financial reason for removing the variation in pay between instructors and special education teachers, which can be up to Pounds 9,000.

The sums involved were not large compared to the overall budgets and councils had discretion over how they spent their money.

“The financial consequences to the respondents (the authorities) of success for the present applicants (the instructors) are small in regard to their budget,” Lord Johnston states.

A further 114 instructors have submitted equal pay claims but the tribunal believes that not all of them will be successful.

Lord Johnston also turned down the councils’ argument that the case should not have been brought under the 1970 Equal Pay Act when there was no direct sex discrimination.

Lord Johnston maintains that the case was about discrimination between two groups of workers, teachers and instructors, and all the latter had to do was compare a man and a woman to fall within the Sex Discrimination Act.

“The absence of sex discrimination is not in itself a critical element, ” he says.

In a further telling section, Lord Johnston argues that “if like work is being performed, and with a difference in qualifications, the proper view of the matter is that the teachers employed in these schools are working to a standard below their actual qualification”.

The appeal tribunal judgment could now reactivate the equal pay case of nursery nurse heads on APTC conditions who were claiming parity with headteachers.

The nurses withdrew their cases after the Court of Session ruled against 10 women members of the Scottish Secondary Teachers’ Association who claimed equal pay with principal teachers.

The SSTA is appealing against that appeal tribunal verdict to the House of Lords.