I took the 11-plus in Northern Ireland in 1971. I found the exam easy and finished before the end. A week later, it was alleged that some schools in the local area had shown the test papers to pupils before the official date - we had to resit. Second time around, I got stuck on one question and spent too long on it. A few weeks later the dreaded envelope arrived over breakfast and my father opened it.

“Ah. Bad luck Ben.” I stared at the letter in disbelief. I remember the word “FAIL” in capitals. It wasn’t just my cornflakes that went soggy that morning.

As I had been expected to pass, my father questioned the authorities. “No mistake,” they replied, before carrying on with sublime indifference to my feelings. “Your son only just failed. In fact, if you had lived 100 yards down the road, he would have got a pass. You see, the pass mark is lower in the Belfast District as there are more places available there. Unfortunately, where you live has a slightly higher pass mark.”

So I went to a local secondary modern school where I knew no one, got completely lost on the first day and vowed never to return. But I survived the year, the teachers were hard working and friendly, and I made friends by being good enough to get into the school football team.

A year later we moved to Bristol, and I moved to one of the new comprehensives. Since there were no 11-plus exams in the area, I was not treated as a failure. It soon became clear that I should take O-levels not CSEs, and that I could do very well. I am forever indebted to the comprehensive syste, and to the staff of Ashton Park school in particular. They set me on the road to eight O-levels, three A-levels, a university geography degree and a PGCE. I have an MA from the Open University. The11-plus is the only exam I ever failed. Dammit, I even passed my driving test first time.

So did I accept the teaching post at the grammar school? I did, as I needed a job, but Ididn’t stay long. The area reorganised into a comprehensive system soon afterwards and I moved across town to a secondary modern that was in the process of turning comprehensive.

What struck me most there was the number of pupils who had failed to be selected for the grammar school yet would not have been out of place there. It became clear to me that about one-fifth of the intake was made up of children who had just failed the 11-plus, or who had an “off” day. These are the sort of children we comfortably push to “five or more A to Cs” in my current comprehensive.

As a system to determine the secondary education a child should have - and their potential for academic achievement - the 11-plus clearly makes mistakes. Lots of mistakes.

Now I work in an 11 to 16 comprehensive that caters for a truly comprehensive intake. Some pupils take 11 GCSEs, others take fewer exam-based courses and have a more vocational flavour to their curriculum, such as going up to the local FE college one morning a week or learning car maintenance on the local industrial estate.

Our pupils are tested every term. The difference is that a test taken at the age of 11 does not predetermine each child’s entire secondary school life. Those in favour of maintaining the grammar system should consider that it might be their child who has an off day and fails. No one who has been through such a grim experience, and who has an ounce of humanity, would want to inflict it on their children.

Ben Warren is deputy headof Ercall Wood technologycollege, Telford