Boys in the former approved schools sometimes defecated when waiting for the next whack of Lochgelly leather on their buttocks, Scottish Office inspectors protested in 1966. They reported almost 1,000 floggings that year.

Papers released under the 30-year rule show rising concern throughout 1967 about punishment beatings in approved schools and children’s homes, sparked by a government inquiry south of the border and press outrage.

The Labour administration at the Scottish Office pressed for the gradual elimination of corporal punishment and, privately, officials acknowledged extensive ill-treatment. “Curious things went on at Guthrie’s Girls’ School (Edinburgh) and Wellington School (Penicuik) for many years,” the inspectors stated.

Geilsland, a Church of Scotland-run school in Beith, Ayrshire, had the highest number of punishments among the country’s 26 approved schools. More than 250 punishments took place in an 18-month period. Mr A Munro, the head, was told there was “no justification for striking or cuffing” and was warned about his behaviour.

Mass revolts were avoided narrowly in several schools and one at Mossbank, Glasgow, was “hushed up”. Staff at several schools were afraid to express their concerns because of the “terrifying power” of the heads.

An inspector wrote his briefing partly in long-hand to avoid the Scottish Office typist anguish and embarrassment. “Corporal punishment is still quite a savage business and . . . boys scream when a stout Lochgelly is applied on their buttocks . . . The records show that many floggings are administered in our schools. Nor am I in any doubt about bruised buttocks which show scars long after the event; this would be particularly the case when special thin pants cover the behind. These are, of course, made of ‘ordinary cloth’.”

He continued: “The instrument is a light tawse. What is ‘light’? It is all quite legal but at times so brutal that boys defecate when waiting the next whack. I am sure that if outside MOs were reporting publicly on the effect of such a flogging many members of the public would be glad to know these young ‘thugs’ were getting the right medicine. The more humane minority would be shocked.”

Later in 1967, a Scottish Education Department official revealed: “While there were complaints from various sources about Guthrie’s Girls’, which should have alerted everyone concerned, there were none about Wellington. Boys do not know their rights, nor do their parents. Sometimes staff do not know the rules. Boys and parents expect severe punishment in these schools and will complain only occasionally and sometimes after persistent breach of the rules over many years.”

But Bruce Millan, the Education Minister, was advised against abolition. “The associations and schools are fully aware of our views on corporal punishment, and any declaration now of an intention to eliminate it at an early date would be regarded by the approved schools not only as a failure to recognise and support them in their undoubted difficulties but as a handicap in the sense that it would create uncertainties before positive alternatives and a change of attitude could be achieved.”

Officials added: “It might have the effect, too, of inducing irregular and concealed punishment.”

Mr Millan was told that “irregular, unrecorded and excessive punishment is by definition very difficult to detect”.

New guidance about the extent of punishments was issued to approved school headteachers, one of whom was removed after Scottish Office investigations. Another deputy was forced to quit.

The process of eliminating corporal punishment in all schools was accelerated by a special committee, including representatives from the teaching unions. But Judith Hart, Mr Millan’s predecessor, was advised in early 1966 against setting up pilot projects. This might set back the trend towards abolition, officials warned.

A committee on alternative sanctions was told by the Scottish Secondary Teachers’ Association, which favoured abolition, that “somewhat paradoxically, the treatment of minor offences appears to present the greatest difficulty. The firm view was expressed that for this type of offence the best treatment is swift, summary justice - in fact corporal punishment.”