Local authority education bosses warned the education secretary that “an overly strong focus” on the Higher pass rate could result in schools stopping “borderline” pupils from sitting the qualification.

Education directors’ body ADES made the comments in an analysis commissioned by education secretary John Swinney in the wake of last year’s exam results.

Mr Swinney has come under fire from the Scottish Conservatives in recent weeks for failing to make the reviews he commissioned of last year’s exam diet public. Last week, he committed to doing so.

Background: Review of Higher pass rate to be published

Related: FMQs row over review into falling Higher pass rates

Figures: Higher pass rate falls

SQA: Exam changes ‘had no significant impact’

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That information has yet to transpire but today, after the publication of responses to freedom of information requests, Tes Scotland can report the advice that Mr Swinney received from ADES and also from the Scottish Qualifications Authority (SQA).

Mr Swinney asked for the “distilled analysis around the 2019 results” after the Higher pass rate fell by 2 percentage points between 2018 and 2019, from 76.8 per cent to 74.8 per cent - a fall that has been much debated in the Scottish Parliament.

However, ADES advised Mr Swinney that too much emphasis on driving up the Higher pass rate could have “unintended consequences”, given that one way to improve the number of A to C grades would be to stop pupils in danger of failing the exam from sitting it in the first place.

The education directors added that changes in the way Highers were assessed last year after the unit assessments were removed - with longer exams in many subjects and exams in subjects like dance that had previously had none - could be responsible for the drop in the pass rate.

The papers also reveal that, in its analysis, the SQA earmarked English, maths, history and psychology as the main subjects responsible for the drop in the Higher pass rate - although the body said it would “expect to see some variability year-on-year”.

In psychology, the proportion of pupils gaining an A to C grade fell 13 percentage points from 57.6 to 44.6 per cent; in history the pass rate fell by 9.8 percentage points, from 82.6 to 72.8 per cent; in English it fell 2.7 percentage points from 75.9 to 73.2 per cent; and in maths it fell 2.1 percentage points, from 74.5 to 72.4 per cent.

However, the SQA stressed that “all assessments performed as intended” and that “no major issues were identified” for subjects with extended question papers.

The SQA added: “Similarly, subjects with new question paper assessments as part of their overall course assessment have performed as expected. SQA is confident that the balance between coursework and question paper in these subjects is proportionate to the skills and knowledge required and that they are benchmarked at the appropriate SCQF [Scottish Credit and Qualifications Framework] level.”

In its submission, ADES said that 36 out of 38 Higher subjects had “changes to Higher question papers” and that “inevitably, these changes require a period of adjustment for teachers and schools”.

ADES added: “It is worth highlighting that pass rates are only part of the ‘attainment story’. It is possible that an overly strong focus on increasing Higher pass rates could cause unintended consequences at school level that impact negatively on some young people. Pass rates can be improved by removing pupils who are on the borderline of passing a Higher course. An overly cautious approach driven by a focus on pass rates may lower aspirations and limit the chance for some pupils to sit and potentially pass their Higher.”

The changes to the Higher exams that came into being last year were made to compensate for the removal of unit assessments. These had led to a “testing treadmill” in schools, according to the EIS teaching union, and were taken out by Mr Swinney in a bid to tackle teacher and pupil workload.

However, the knock-on effect that removing unit assessments had on Higher exams and coursework was controversial, with teaching unions arguing that the changes went too far.

The SQA said “the main subjects” contributing to the lower pass rate at Higher were English, maths, history and psychology.

Last year’s Higher history exam consisted of two papers - as opposed to just one - and was 40 minutes longer than in previous years.

The Higher maths exam, meanwhile, was extended by 35 minutes in total and psychology by a total of 40 minutes.

There were no changes to the English exam but a spoken element was added to the coursework required for the qualification.