A few months ago, I was sitting in the headteacher’s office at a large, inner-city secondary school when a student was brought in by one of the deputies. It turned out that the student had been accused of threatening another child with a knife.

The mention of a knife instantly increased the tension in the room, particularly because its presence had not yet been confirmed - and, if the boy did have one, it was still on his person.

The deputy calmly told the boy that he would have to be searched, the school would investigate and take appropriate action and his parents would be informed. The boy looked defiant and upset. It was clearly a potentially dangerous situation.

The headteacher intervened and told the boy in a calm, measured tone that he was in serious trouble, but that the best way out would be for him to produce the knife. They could then work out a way of resolving the situation, she said. The boy handed over the knife and everybody - the student included - breathed a sigh of relief.

Such incidents are not uncommon in urban (and rural) schools, and a vital part of successful school leadership is to develop strategies to deal with them. What struck me, though, was not simply the efficiency with which the headteacher and her deputy dealt with the boy, but the courage it took to maintain control in a moment of extreme pressure.

I recently interviewed 20 of the UK’s most experienced headteachers for the book 8 Qualities of Successful School Leaders, and instances of real courage came up time and again in their stories of success.

Madeleine Vigar, now principal of the Castle Partnership Academy Trust in Suffolk, south-east England, provided two examples. The first is from when she was newly appointed to a leadership role. She had taken over Castle Manor, a troubled school, and turning it around was incredibly challenging.

“There’s a mental courage, that you don’t waver,” she says. “It was the determination that Castle Manor was going to be the best school in Suffolk and the children deserved the best.”

To continue in the face of adversity and to stick to her principles when instant rewards would not have been forthcoming was courageous, as was taking on the school in the first place.

The second example occurred during a visit by school inspectors. A boy known to be volatile had come into school with a golf club and was intent on injuring another student. Vigar called the police and, with the support of two colleagues, intercepted the student and prevented the incident from escalating.

Sue Hargadon, headteacher of Farlingaye High School in Suffolk, provides a different example. Early under her leadership, a child pushed another student through a bus window and she opted to call the police. This came under scrutiny as parents and other parties became involved, yet she held firm that her decision was the right one, despite having inevitable doubts.

“I can remember going home and not sleeping all that weekend. I was so worried about what I’d done, and whether I’d taken the right action,” she admits. But she says that holding firm meant she was “telling everybody that I was not going to back off, that I will be there to be counted, and I was really glad I did it”.

Whether you are taking on a violent student, trying to turn around a failing school or having faith in your convictions, you are displaying mental courage, an unwavering determination to see things through whatever the circumstances.

This sends a clear signal that you are a strong and decisive leader. It also draws teams together and strengthens a school’s culture and values. It demonstrates that you are in charge and unafraid to show it. Courage is not always easy - and not something you can necessarily learn through training - but it is an essential component of successful school leadership.

Jeremy Sutcliffe’s book 8 Qualities of Successful School Leaders: the desert island challenge is published by Bloomsbury and priced at pound;16.99

In short

• You need mental courage and determination to be a school leader.
• Don’t avoid difficult decisions, especially when they concern student behaviour or underperforming staff.
• Focus on priorities that really matter to the strategic direction of your school.
• By making a stand on the big issues, you can significantly strengthen your school culture, ethos and core values.