For literacy and numeracy at the senior levels, schools will be expected to have 96 per cent of their fourth year achieving a Standard grade 1-6 in English language and maths, an absolute target that will not be influenced by free meal variations. Schools achieving below that level will be expected to halve the gap between their current performance and the 96 per cent target. Schools above the line will be asked to maintain or improve on their showing.

HMI says schools and authorities that can demonstrate “exceptional circumstances” will be freed from this Standard grade target. These circumstances are deliberately left vague in the Setting Targets proposals, although they are understood to refer to changing circumstances.

Five other targets relate to the number of fourth-year pupils achieving five or more Standard grades at 1-6, 1-4 and 1-2, as well as the numbers gaining three or more Higher passes and five or more Highers in fifth year.

The school characteristic index (SCI) target for Highers will be derived from free meal entitlements and previous attainment of pupils at Standard grade 1-2. The audit unit believes the latter measure will answer charges from councils dominated by the leafy suburbs, such as East Renfrewshire, which say an index based on free meals would be meaningless.

Based on current performance and benchmarking information, HMI estimates that an additional 7 per cent of fourth-year pupils could achieve five or more Standard grades 1-4, currently reached by 72 per cent of the year group averaged over three years. The increase would represent another 4,200 pupils, or an additional 10 pupils in the average secondary school of 800 pupils.

Frank Crawford, the head of the audit unit, stressed that “no school would be set unrealistic targets”. To avoid that the targets would be related to achievements of the 40 most improving schools, not those with the best results.

Mr Crawford promised HMI would provide support for schools in the form of materials showing how some schools have been able to raise attainment. There will also be a targets “roadshow”.

The Secretary of State stressed that the targets would not be “a soft option.” But schools should have little difficulty in meeting them because they were “achievable.” The emphasis was on “support and improvement not crisis management,” the Educaion Minister said in rejecting a “hit squad” approach to failing schools.

Mr Wilson added: “The approach is built on a very simple principle - schools should seek to do as well as similar schools that are doing better.” Schools will also be able to adopt their own wider targets.