You’d think that, after 25 years, I’d know everything about our school building. I know what to do when the boys’ toilet overflows and where to find lost coats that children swear have been “stolen”. I can advise attention-seekers of the best spot for jamming their heads in the railings so that we have to call out the fire brigade. I know that children always take the longest route from their classroom to the school office to extend their freedom. I know that, in a previous existence, our playground was an orchard. In short, no one knows the building better than I do.

I know that the tall windows running the height of the staircases at either end of the school are typical of 1930s design. Their proportions ensure that the stairs are always flooded with light, although it puzzles me why the stairs are bathed in natural light when corridors and classrooms are deprived of it. At least the lack of light, and the afternoon stuffiness to which the building is prone, will belong in the past when we occupy our new school in two years’ time. “Whatever else you do, make it light and airy,” is my repetitive plea to the architects.

Yet, recently, I’ve sustained two major shocks. The first has been to discover that I don’t have an encyclopaedic knowledge of our building after all and the second is the realisation that our local council, supposedly guardian of our welfare, has been trying to asphyxiate our staff and pupils and endangering our eyesight for the past 40 years.

My eyes have been opened by a book which, among other issues, looks at the Government’s concern about children’s poor health. Don’t expect the usual parade of obesity, fast food, and overprotective parents. Health concerns are not new and this book refers to the time when my 80-year-old mother was at school and McDonald’s and paedophiles hadn’t been invented.

The Scottish Thirties: An Architectural Introduction, by Charles Kean (Scottish Academic Press, 1987) examines the social and technical influences on Scotland’s new buildings in the inter-war period.

In a chapter entitled “Fresh air and fitness”, Mr Kean describes the problems faced by school planners of the 1930s. He writes: “A large number of school children came from insanitary slum dwellings in bare feet and carrying disease.”

To improve health, architects incorporated into their new schools features which would protect against infection and dissipate smells, as well as providing more cheerful surroundings. Sunshine, light and air would be the watchwords. Many imaginative designs were tried. Ours was one of the cheapest, of course, but it fulfilled its brief. Most of the classrooms are south-facing and natural light from the tall staircase windows streamed into the corridors. Careful positioning of entrances meant that cleansing fresh air swept through the building when required and a row of windows, high on each corridor-side classroom wall, could be controlled to allow fresh-air gusts into the room. The means for admitting light and air are admirable in their simplicity.

So what’s my problem? Just that, 30 years later, most of the work was undone by the ignorance of council officialdom. In the name of fire prevention, they sealed in the two staircases with solid, permanent walls, thereby cutting off the corridors’ natural light. Extra doors were added throughout, reducing any likelihood of a fresh-air flow. Together, the new staircase walls and the additional doors create a stuffy, and less than hygienic atmosphere as each day progresses. How’s that for destroying an effective design?

If you have a new school, remember that knowing your building is about more than counting coat pegs and gym fittings. Understand the rationale of its design and make the best of it before it’s too late. People who should know better will try to undermine it.

Brian Toner is head of St John’s primary, Perth.