IT STARTED as an ordinary day, but Tuesday 11 January 1977 has remained etched in my memory. That afternoon, while teaching a group of fifth-year pupils in a comprehensive school in Tottenham, I was attacked by an intruder, and was stabbed in front of the pupils.

My heart goes out to the family of the teacher Ann Maguire, the staff and pupils at her school, and the wider community caught up in the recent tragic events in Leeds (News, 2 May). My experience has remained with me for ever, as it will have for the others who witnessed it. I could not watch plays such as Macbeth, or any violence involving knives, for many years.

In the 1970s, there was no counselling available either for the pupils who saw the stabbing or for the wider school community. We have moved on in this respect for what still remain rare events in schools. There have been about nine million teacher-years spent in classrooms since the head teacher Philip Lawrence was killed outside his London school (like the school in Leeds, a Roman Catholic secondary) in 1995, and the shooting in Dunblane a few months later in March 1996, where a teacher and 16 pupils lost their lives.

It is important to recognise that violence still exists in many secondary schools, but, despite some comments, not at the level witnessed in the past; and corporal punishment is happily nothing but a distant memory. Nevertheless, the worrying spate of different types of attacks on teachers since the Leeds event once again raises disturbing questions.

Nearly 40 years ago, my attacker spent a short period in custody as a juvenile - less than would be the case now, after the concerns over knife crime during the past decade. Both the Court of Appeal, in recently backing deterrent sentences for knife crime, and ministers' proposing mandatory sentences, that leave courts no discretion are trying to use punitive means to eradicate such crimes.

After serving for more than 20 years as a magistrate, I have no faith in mandatory sentences decided by Parliament. Westminster should decide the maximum sentence an offence deserves, and then leave the sentencing to the judiciary, assisted by their guidelines.

Similarly, although any fatality must cause organisations to review their policies on preventing intruders' gaining access to schools, and other measures for the protection of staff, I do not believe that every school should rush to introduce metal detectors. They can cause a false sense of security.

I once visited a school in the United States which had full airport-system protection, with metal detectors and bag searches. Sadly, the day before my visit, there had been a shooting: a gun had been handed in through a ground-floor window. Better to create a situation in schools where bullying and fear are dispelled and pupils see no reason to bring weapons on to the site.

Learning is all about building trust, and sometimes taking risks based on that trust. As I look back on my career in education since that day in 1977, I reflect how lucky I was, and give thanks for the support of my family and friends, and those who helped me when I returned to my classroom six weeks afterwards.

I still believe that education has a duty to reach out to all and seek to improve lives, not merely to contain young people. Schools are much better at this than when I was stabbed, and I firmly believe that we must see the recent tragedy in Leeds as a time to reaffirm our commitment, and not to pull up the drawbridge and retreat into a fortress mentality.

Professor John Howson JP is a Liberal Democrat county councillor in Oxfordshire, and a visiting professor at Oxford Brookes University. He taught in Tottenham for nine years, and has since worked in teacher education, and owned an education-research business.