We practitioners of education, the soul of a society, have witnessed the vulnerable walls of childhood terminally breached by the alien and violent. Dunblane reached the higher realms, not just of psychological stress, but of disillusionment for us as teachers. Taken in conjunction with the death of London headteacher Philip Lawrence, sustained in an effort to protect his pupils, things can never be exactly the same again.

I have every affinity with most of the reactions that followed immediately. I’m sure every school reviewed its security practices the following day. Certainly I did, and expressed impatience with the extent to which they did not come up to scratch. No one complained when I replaced the personal attack alarms that have been standard issue for some years. The longer-term implications of how far the duties and responsibilities that teachers have for the safety of children within school can and should extend, and just what responsibilities local authorities have to protect teachers and pupils, are a different matter that will occupy the policy-making community for some time to come. Certainly they have exercised me.

Two decades in the same building have shown me that the accumulation of small changes in workplace environment taken individually make little or no impression, but collectively and cumulatively have ensured that the whole atmosphere and appearance of the school have changed. And not for the better. When I arrived, five keys were needed for the whole school. Now there are enough to make a professional turnkey call out his union.

The building once had clearly visible gutters, edges and corners. Now they are hidden behind a zariba of roll-bars that snake around the building and make it look like a galvanisers’ throwaway bin. Unremittingly ruthless burglaries have thrown so many security trip-wires that the great adventure of going to school for a lot of our children means moving into a secured perimeter behind bars and wire guards, protected by steel doors with interior push bars and surrounded by plastic windows, where an alarm system winks at you where’ere you walk, and where your teacher has a personal alarm. That’s just the inside.

Recent years have seen an increase in human activity within the playground areas in daytime. Daylight hours see a never ending procession of dog walkers, whose beasts are either on a long lead or a short fuse, roaming adolescents who seem never to attend school, but find schools irresistible places to loiter in, and various abusers of controlled substances. Most irritating are the bands of footballing vagantes with attitude, ready to rattle your wire guards and keen to clean your clock, while offering, sexually speaking, technical challenges that pique the imagination.

I used to remonstrate gently, reminding them that we were in the business of education, not leisure facilities. Not now. I don’t know what they are carrying or abusing. Instead I regularly contact my clerk of works who last year offered enough palisade fencing to make the region change the name of the place to Stalag Luft Ogilvie. I vacillated too long, for aesthetic reasons. Perhaps that was a bad judgment call.

Trouble is, all this has been undertaken to protect the building and its contents, not its most fragile, most valuable ingredients. The Catholic service of compline has a section in it detailing what the believer will be protected from. It includes “the arrow that flies by day, the plague that prowls in the darkness and the scourge that lays waste at noon”.

We should all say amen to that, and hope that the worst that happens is the opportunist thief.

Joseph Kelly is headteacher of Ogilvie primary, Glasgow.