But George MacBride, education convener, accused the Higher Still implementation studies of being no more than a “dream” which had not faced up to the reality of larger classes in secondaries.

There was no indication the Government was prepared to pay for staff development, new course material or enhanced staffing. Ministers had set aside Pounds 5 million to get the scheme going, yet this was only Pounds 1 per head of population.

Myra Armstrong, Edinburgh, said teachers were concerned about levels of internal assessment and “less rigorous and less fair” procedures, biased towards the approach of the Scottish Vocational Education Council and away from that of the Scottish Examination Board.

Bryce Wilson, East Ayrshire, criticised the council’s “star billing”. He told delegates: “They tell us to write our courses and assessments ourselves and send a moderator to our school to criticise our efforts.”

Meanwhile, left-wing attempts to force the pace on smaller class sizes were heavily defeated. Motions from West Dunbartonshire and Edinburgh were countered by Peter Andrews, the institute’s salaries convener, who argued that progress would only be “gradual and incremental”. A feasible target was a reduction in primary 1 class sizes.

John Patton, Clackmannanshire, a primary headteacher, said he would shortly have to tell parents that there would be four composite classes and three at the maximum of 33. But nothing would threaten the teacher alliance with parents more than industrial action.

James Kane, West Dunbartonshire, replied that the union had “achieved nothing” and that a future Labour government was unlikely to be sympathetic. Action should begin by December if negotiations had not progressed.

Mr Kane declared: “Come December, if the Government has not reduced class sizes, if a class of second years comes in and there are 30 pupils there, you say to four or five of them, we refuse to teach you.”