"I have greatness within me."

That was the message Dr Stephen Addison got every child in our assembly to recite together this morning, and it set the tone for one of the most powerful visits William Ford has ever hosted.

Dr Stephen Addison has built a career around changing lives. He is a boxer, the founder and CEO of social enterprise BoxUp Crime, a British Empire Medal recipient for services to young people, and an honorary doctor of letters. BoxUp Crime delivers boxing training and mentoring to more than 2,000 children and young people every week, with reach across the UK, Switzerland and Ghana. Around 50,000 children have been touched by his work.

He spoke with remarkable honesty about his own story. His journey onto the wrong path began in primary school and continued into secondary. He was expelled, joined gangs, and came close to prison. And then he discovered God, and the direction of his life changed completely. The career he has built since then has been dedicated entirely to making sure others don't have to travel the same road.

He spoke to our children about forgiveness: that whatever has been done, it can be forgiven. He spoke about how no path is fixed, and that the moment you choose a different direction, things can change. And he spoke about reach: how the career you build can touch far more people than you ever expect.

For our children, some of whom face real pressures and challenges of their own, this was not just an inspiring story. It was a personal one. And as a Church of England school, the message that God can be their inspiration, their forgiveness and their guide sits at the very core of what we believe.

The headteacher also ended up in a boxing sparring demonstration. After having his colours analysed and being part of a magic trick in previous assemblies, our career visitors are keeping him very much on his toes.

We are deeply grateful to Dr Addison for his honesty, his warmth and the extraordinary morning he gave us.