In February of this year, Nadia Mendoza, who is one third of my Self-Esteem Team, received a telephone call to tell her that her 24-year-old friend James Mabbett (or “Mabs”, as everyone called him) was dead.

The effect on her was immediate and profound. He had been her reliable pal for merry-making, Nadz told me, always the first to get a round in and always with a smile on his face. She confessed that she hoped, in a macabre way, that perhaps he’d “overdone” it at a party, because at least then he would have died doing something he loved.

When, a few days later, it was confirmed that Mabs had quietly hanged himself in his hotel room on a work trip away, with minimal alcohol in his system, Nadz spiralled into a cycle of self-criticism and questions we, as friends trying to support her through her grief, simply couldn’t answer. Why hadn’t she noticed anything was wrong? What could she have done to stop it? Why hadn’t he said anything?

Nadz eventually came to an important conclusion. She works in mental health. People confide in her all the time about their most intimate struggles. Yet these aren’t the people she should necessarily be the most concerned about. After all, they were talking about it. Mabs never gave Nadz any indication that he was having suicidal thoughts. He had a default mode and it was always set to “happy”. But, Nadz realised, having one consistent mood, even if that mood is positive, isn’t normal for anyone.

For Mental Health Week in May, we made a Youtube video “Switch on the Light” featuring seven high-profile men, including Stephen Fry and Professor Green. We asked them a simple question: Tell us your worry. These varied enormously from “will I be a good parent?” to “I never feel that I deserve the things I have been blessed with”. We edited them together in an attempt to show that emotions don’t emasculate.

The video was quickly endorsed by several branches of the Samaritans and NHS Trusts and, spurred on by its success, we began researching in all-boys’ schools, with a view to creating a “Switch on the Light” class specifically targeting male mental health.

After conducting focus groups with hundreds of boys and young men, ranging from 11 to 18 years old, the recurring themes were crystal clear. Boys at the younger end of the spectrum told us that, while they did sometimes want to discuss how they were feeling, they were prevented from doing so out of fear of “banter”. They were almost certain, they told us, that any kind of emotional confession would result in “piss-taking” and that, by the end of the day, the entire school would know.

Older teenage boys expressed similar sentiments with regard to “banter”, but were (ironically enough) actually bantering with one another while they were telling us this. We asked them, if they hated it so much, why they were communicating with one another in this way. They replied that this was, simply, their only blueprint for man-to-man communication. That every man they knew - their dads, brothers, uncles, every other boy in their school - spoke to each other in this way.

How do you solve a problem like banter?

This was a conundrum we, as three women, were ill-equipped to solve. The merest glance at social media reveals hundreds of blusteringly furious young men convinced that “feminists” are trying to “turn them into women” (a dubious, but apparently very real concern). We didn’t want to inadvertently wade into this particular ludicrous online gender war, when we were simply trying to help.

We called to the rescue a psychologist with 30 years’ experience, the rather brilliant Martin Seagar, who is now a specialist in male psychology. He was characteristically frank. “Look,” he told us, “there is absolutely no point in telling boys that they don’t need to be strong. It’s built into their psyche that they want to be seen as strong. The message just won’t compute. What you need to do is redefine what strength is.”

So, that is what we are attempting to do. With the support of Steve Mallen (founder of the MindEd Trust), Alex Lyons-Negus (from the office of Heidi Allen MP for South Cambridgeshire/SuperWoman), Johnny Benjamin (star of The Stranger on the Bridge and mental health campaigner), Paul and Caroline Vodden (anti-bullying campaigners) and Martin Daubney (one of our “associate lecturers” who manages rather brilliantly to engage teenage boys on the subject of online porn) we descended on the Leys School in Cambridge last week to present our first ever “Switch on the Light” assembly.

We targeted Year 11 and sixth-form boys, hoping that if we could make them sufficiently aware of the issues, as well as of the power they wield as role models to younger boys in the school, their example would have a ripple effect. We told them that they didn’t have to talk about their feelings all the time, we were simply asking them to create a culture where it would be possible for one of them to express an emotion if they wanted to. We asked them to tell us environments where they felt most comfortable talking, acknowledging that might be when they are doing something else, like exercise. We asked them to think about the sort of men they wanted to be and what “strength” and “masculinity” really were. An example of bravery might be speaking out when “banter” has crossed over into bullying, or seeking help for mental illness despite there still being so much stigma, we suggested.

Afterwards one student emailed us to say how thought-provoking he found it. He told us that half our audience had found the assembly “totally pointless”, believing that men would never change and that being stoic was the real sign of strength. But the other half, he said, were discussing the issues we presented for a long time in the common room afterwards and were galvanised to try to make a positive change.

A 50 per cent success rate isn’t bad for our first go, but clearly there is still work to be done. I believe, in a world where suicide is the biggest killer of men under 50, accounting for one in four deaths among that demographic, we need to work harder to frame mental health in schools in a way boys will relate to. I’m hoping that my team and the people who are supporting us can lead the charge.

As ever, dear TES readers, any suggestions you have are very welcome (@natashadevonMBE on Twitter).

Natasha Devon is the Department for Education’s mental health champion

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