Tempers started to fray at the end of the schools management conference in Edinburgh, with a number of delegates unhappy at flak being directed at secondary schools.
They reacted after Jim McColl, one of Scotland's richest entrepreneurs, had outlined his plans to open a school with a vocational emphasis in Glasgow next year, aimed at the 20 per cent of pupils aged 14 to 16 for whom he felt school was not working.
Mr McColl had underlined that secondary schools did well for most pupils, and revealed that 10 headteachers were working with him on what will be known as Newlands Junior College, set up in a disused building on the site of his company's factory in Cathcart, Glasgow.
But some delegates became irked by the tenor of debate after Tina Woolnough, of the National Parent Forum of Scotland, told Mr McColl that secondary schools were "fundamentally not inclusive" and that the proportion of pupils for whom school did not work was higher than 20 per cent.
"I don't think it's right that our high schools are taking a battering at the end of this conference," said Ronnie Boyd, an education officer in West Lothian.
There was a spontaneous round of applause from a large proportion of the delegates. Paul Raffaelli, headteacher of Dunbar Grammar in East Lothian, stood up to say he had been about to make the same point, and pointed out that 98 per cent of pupils at his school left with five or more qualifications.
Mr McColl, who oversees an annual turnover of more than pound;1.35 billion as chairman and chief executive of Clyde Blowers, had earlier spoken of his desire to start a school next August for pupils who prefer to "learn by doing".