The ironic outcome is confirmed by the latest set of figures on exclusion, published on Tuesday, which showed there were 36,496 cases of exclusion in 2002-03, a drop of just under 3 per cent on the year before.

The total for last session represented an average of 50 cases for every 1,000 pupils in primary, secondary and special schools. But this soars to 109 per 1,000 for pupils who have a record of needs, 120 per 1,000 for pupils on free meals, and 227 per 1,000 for the most vulnerable group who are in local authority care.

Peter Peacock, Education Minister, welcomed the “downward trend”. Having radically altered the exclusion agenda since he came into office by putting headteachers in the driving seat, Mr Peacock said he wanted the trend to continue - “but as a result of best practice being shared among schools, not national targets”.

The Scottish Executive will be re-examining the reliability of the statistics as part of its overall check on the evidence of school indiscipline, announced in response to figures on violence against school staff released last month.

It is not clear from the exclusion figures whether greater inconsistency or growing indiscipline lies behind the variations among education authorities - reinforcing the unreliable picture that concerns Mr Peacock.

Exclusion returns show 91 per 1,000 pupils in Dundee but only seven were recorded in Shetland and the Western Isles. Dundee also tops the league for the number of primary school exclusions and is second to Glasgow in the rate for secondaries.

A statement from the city’s education department noted that the number of exclusions had fallen by 6 per cent over the two sessions compared with the 3 per cent national decrease. The length of the exclusion period in Dundee schools had also fallen for the third year running.

The council insists it uses exclusion only as part of a range of measures to improve behaviour. It has a number of initiatives aimed at warding off exclusion where pupils are thought to be most at risk, including sending pupils out of school, providing support bases in school and introducing an alternative curriculum.

There are also considerable variations between the sectors - 10 per 1,000 pupils in primary, 98 in secondary and 173 in special.

Again, different authorities vary widely. Dundee’s 19 cases per 1,000 primary pupils compares with one in Shetland and the Western Isles; Glasgow leads the secondary figures with 188 cases per 1,000, while Shetland and the Western Isles have the fewest exclusions, recording 13; and special schools have the greatest range of all, from 605 per 1,000 in Falkirk to six per 1,000 in Highland.

The number of exclusions fell in both primary and secondary sectors while cases in special schools continued to rise.

Of the 36,496 exclusions, 36,204 were temporary. Only 292 pupils were completely removed from the register of their school, 12 per cent fewer than the year before.

These figures are not affected by the change in the Executive’s policy of dropping exclusion targets, revealed in The TES Scotland last May but not given force until a revised circular was issued in November.

Rod O’Donnell, Scotland Plus 9