The head of the Glasgow school that has set the pace in streaming pupils expressed his disappointment at "patchy" results in this year's exams.
Rod O'Donnell of St Paul's High in the city's Pollok area saw the top Standard grade Credit passes fall from 14 per cent to 4.4 per cent, while General passes slumped from 68 per cent to 48 per cent. Mr O'Donnell said his disappointment was not just for his staff but for the pupils.
The school would now investigate in detail why some of the results did not live up to expectations. But he insisted that the real impact of streaming would not materialise until next year. This year's incoming S4 includes a group who have been streamed for the full four years.
"That is the group we are really tracking," Mr O'Donnell told The TES Scotland. "So next year we will be fair game because people will be able to say, well you've had them for four years - what's the result?"
He attributed some of the fall-off to "the normal fluctuation in the performance of year groups". The school had not held out high hopes for last year's fourth year which he described as a "hybrid group", who had started out in mixed-ability classes in S1 before streaming began in S2.
But Mr O'Donnell added: "The disappointment is still real enough, particularly since this year's results buck a trend where the picture had been improving."
Claims for the success of the school's approach led to a row in June when Hugh Reilly, a union figure there, suggested they were misleading. The head was then reported as suggesting that Mr Reilly only spoke for about three members of the Educational Institute of Scotland. Mr Reilly accused Mr O'Donnell of a "slur on my reputation".