A call from John Kelly, East Dunbartonshire, to take industrial action, if necessary, to resist the removal of guaranteed correction and preparation time won unanimous support.

Mr Kelly told the conference that the most important thing teachers had gained from the Houghton inquiry in 1974 had been guaranteed non-class contact time for preparation and marking. “We never gave up that condition of service - until we came to the McCrone settlement,” he said.

Next year progress on implementation of the agreement would be reviewed so that teachers could move to a less rigid timetable for the hours beyond their 22.5-hour commitment to teaching classes.

Mr Kelly warned: “When you find that the number of teachers to bring English and maths classes down to 20 in S1 and S2 has not quite materialised, you will be in front of them (the classes). It does not matter that you are a science or French teacher, because management will be able to say that your conditions of service guarantee you a 35-hour week, 22.5 hours of which is a timetabled commitment, and the other hours are at the discretion of the headteacher.”

Management wanted to get its hands on non-timetabled contact time because it cost pound;165 a day to employ a supply teacher. “You only sell a condition of service once. The first principle of trade unionism is that once it’s gone, it’s gone,” he said.

Mr Kelly also attacked the job-sizing exercise, describing it as “the most obnoxious piece of legislation on teachers’ salaries I have seen in my lifetime”. He warned: “Remember that your local authority employers hate you. You were part of the profession that broke the strike in 1926 and they are going to do you for it.”

Hazel Ralston from Glasgow, a primary principal teacher, said: “A system which pays someone for doing nothing extra while paying someone else the same who is taking on management responsibilities is wrong,” she said.

However, Victor Topping, a member of the national executive, maintained that as a result of job-sizing, secondary school salaries had risen across the board by some 2 to 4 per cent, over and above the McCrone increase.

Delegates, following the example of the Educational Institute of Scotland and the Scottish Secondary Teachers’ Association, unanimously backed a motion urging members to “resist vehemently at local level the destructive aspects of proposals for new staff structures”.

There was no requirement arising from the McCrone report for the introduction of a faculty system, they maintained.