The first thing I did when I came here four years ago was permanently exclude a pupil who had assaulted another pupil the previous term. In my first assembly, Imade it clear that this sort of behaviour would be dealt with.

This was a failing school. The roll was falling, the city was about to face a shake-up in education and there was a possibility we could be the school that was chopped.

We were inspected in my sixth week, and found to have serious weaknesses. There were tensions between black and Asian students, and we had integrated several Kosovan refugees into the school.

We’re completely comprehensive and we have some very challenging youngsters. Students will swear at staff and will fight, in which case we traditionally sent them home or got their parents in.

This is now an upper school and will become an 11-18 school next year. It’s about role models, and it’s about preparing the way for having youngsters of 11 and 12 here.

From September, we decided to exclude pupils for fixed terms to make the point that we were not prepared to tolerate disruptive behaviour. If students fight or intimidate other students, I will formally exclude them. I will also exclude students who smoke on their way home.

Swearing at teachers brings automatic exclusion. I discussed this with the governors last year and I wrote to all the parents. And I made it clear to staff that I did not want them sworn at.

Society is starting to accept that teaching is a difficult job and that teachers should be valued more. Not just in terms of money - it’s also about respect. I have carried out about 100 fixed-term exclusions, which in a school of 560 is quite high. I have carried out three permanent exclusions, two for assaults off site. Around 25 to 30 per cent of the fixed-term exclusions have been for smoking. Only one or two have been excluded a second time. I do it for one day the first time, then two days, then four days, then eight days, then 16 days. The students soon get the message that it will go on their records, and they don’t want their parents coming in for this.

About 95 per cent of parents are fine with the regime; the rest must have that argument with me, and not the teachers - because if there’s a formal exclusion, it’s my decision. I’ve had some challenging situations, but it’s about saying: “No, sorry, our job is to educate. We’ll support students all we can and we’ll work with you, but we won’t have this behaviour.”

There’s been some interest from other schools and some amusement. One or two colleagues pull my leg and say I’m the hitman of Oxford, but I’m not sure that’s true.

The school is now as quiet and purposeful as any I have worked in. The staff are superb and there’s a real sense of moving forward.

Ian Johnson is head of Oxford school in Oxford. Interview by Martin Whittaker