For his final gig, Jonny Griffiths stood in front of a sold-out crowd at London’s Sadler’s Wells theatre. The band filed on stage to raucous yells and whistles. Then the audience began to applaud. For 10 minutes, before the musicians had played even a single note, the audience continued to cheer and whistle.

And then, after the gig, Griffiths hung up his guitar and went off to train as a teacher.

In an identity-switch that would impress a Marvel comic hero, he now lives out his life as a mild-mannered maths teacher at a sixth-form college in Norfolk. “I did sometimes doubt the worthwhileness of some of the shows we put on,” he says. “The music was a bit trivial. It’s the opium of the people, really. Teaching always seemed a very worthwhile occupation.”

Griffiths is not the only teacher to be concealing a superhero-style alter ego beneath his tweed-jacketed exterior. The welcome that teaching gives to career-changers means that high-flyers often find it a tempting option when they are planning to don the glasses of normality and conceal their superhero underpants beneath a pinstriped suit.

“Some pupils think it’s really cool that I was in the paras,” says James Lynch of his pre-teaching career in the special forces. “Obviously they’ve seen lots of films, and they’re pretty action-packed. I suppose they think it’s pretty cool. But it’s just as cool to sit in class and learn, and know how to do your English and maths and science.”

This is by no means a unique perspective. Between 1981 and 1987, Griffiths was vocalist, guitarist and violinist with the band Harvey and the Wallbangers. The band was, for those six slightly crazy years, a household name. But “the last two years were unmitigated hell, from beginning to end”, Griffiths says. “I’d had enough of the high life. My temperament is much better suited to a nine-to-five job. I wanted to sleep in my own bed.

“We were big-time in debt. It became obvious that we weren’t going to get another record deal. And I hated the travelling. Up and down motorways, every day. It was gruelling.”

Lessons learned in Soho

Tom Bennett, too, found that the demands of a high-octane career were leading him increasingly to dream wistfully of a quiet night in with the marking. Bennett, now head of humanities at the inner-London Raine’s Foundation School, had left university with a philosophy degree (“the eternally unemployable degree, unless you become a civil servant”) and very little idea of what he wanted to do with his life. And so he took a job behind a bar in London’s Soho. He eventually became manager of the club.

Over the course of eight years - “I lasted quite a long time: most people last about two years” - he was threatened with knives, had bottles thrown at him and was warned not to leave the club at the end of the night. Once, he removed glass from someone’s foot, only to have that person kick him in return.

“It was quite an eye-opener for me,” he says. “My strangest thing was throwing transvestites out of the women’s toilets. Not because I have a problem with transvestites. But the women started beating them up.” The women had confronted the transvestites, asking them why they were there. The transvestites insisted that they had as much right to be there as the women. And so a fight broke out. “That was odd: throwing a 6ft 5in man out of the women’s toilets,” Bennett says.

“Nightclubs were fun,” he adds. “But very unfulfilling. I wanted to do something that I was proud of. I wasn’t proud of working in nightclubs. That saved me. Otherwise, I’d have wasted my life there.”

Government ministers and teacher training colleges have made a virtue out of later-life conversion to teaching. Life experience, they say, is invaluable in the classroom. A pre-classroom career allows for the acquisition of those much-vaunted transferable skills. And all the more so, surely, if the pre-teaching career involved hardship and adrenaline, ensuring that would-be teachers know exactly how to respond to a class full of belligerent 14-year-olds.

“It was tough,” says former paratrooper Lynch of his years as a trainee teacher. “That was a real challenge. Really, really difficult.”

Some context: during three years as a paratrooper, Lynch jumped out of aeroplanes travelling at 150mph, with more than 50kg of weights tied to his legs. He served in Northern Ireland, where he was shot at often. In between, he ran between 25 and 30 miles a day, weights strapped to his chest. It may be stretching things to say that he could kill a man with his bare hands, but only just.

“I found the classroom a real struggle,” he says. “It was very difficult, coming out of that military world and settling in to university. Independent study was all new to me - I hadn’t done that sort of assignment. Going out, running, coaching a team, I could do automatically. But go and put a 2,000-word assignment together? Yeah, that was very tough. I’d rather have gone out and done a 25-miler than spend two-and-a- half hours in the study.”

But Lynch was accustomed to learning things the hard way. At the start of basic training, all cadets are given the same crew cut, and then handed a randomly selected uniform. “I’m 6ft, but I was given kit that might fit a guy who was 5ft,” he says. “It was up to you to get it sorted. It was a massive culture shock: the brutality and physical and emotional strain put on you.” Of the 80 cadets who began basic training in Lynch’s cohort, only 12 finished.

Jonathan Peel, too, found that his previous career had provided him with the skills necessary to handle new-teacher stress. While Peel was studying Classics at university, a friend had bought him singing lessons as a gift. He turned out to have more than an aptitude for it. Two years later, he had a contract with an opera company. “You think: `Why not?’ It’s quite a fun way of earning a living, for a while.”

By the time he was married with children, however, he began to see things slightly differently. He was away from home roughly eight months a year. This might mean a stint in Glasgow or Leeds, but it could equally well mean six weeks in the US. “You can’t get home at the weekends or on bank holidays or Christmas,” he says, “because that’s when people want to go to the theatre. So you have to perform.”

He knew it was time to quit when his agent called to offer him a job in Naples, and his response was: “Do I have to?” At that point, he recalled his original student ambition to train as a teacher. And so he decided that it was time to revert to plan A.

“I had the tension and nerves that everyone has,” he says of his first terms as an English teacher. “But standing in front of a group of people and delivering doesn’t actually faze me very much. As long as I’m mentally prepared - as long as I know my subject and my material - then I can do it. It’s what I’ve always done. I’m a performer. And that did take a layer of tension out of the first weeks in the classroom.”

Facing a new audience

There is a danger, however, in assuming that, simply because you were capable of captivating crowds of thousands from a theatre stage, you will be able to scale down the act for a crowd of 30. “I thought I could go in there and perform, and they would love me,” says Griffiths, the former musician.

He began his first job, at an inner-London comprehensive, with the idea that he would be a firm disciplinarian. If a pupil was misbehaving, he thought, he would click his fingers, point and say: “What’s your name?” When he tried it, however, the pupils simply started laughing. “What a jerk,” one teenager said. “He was absolutely right,” Griffiths concedes.

“People say that teaching is an act,” he continues. “And being in a band is an act. On stage, everyone’s watching you. But if you try and do that in the classroom, you’re just like a TV in the corner. People just have a chat while you’re talking.

“As a teacher, you have to be interested in the people in your classroom. That’s what teaching is about, rather than just standing there and giving the lines.”

Griffiths was, he says, “destroyed” by his initial teaching experience: “I spent three days and nights not sleeping. In the end, my friends took me to hospital. It took me about 15 years to recover.”

Bennett also struggled with what one might assume was the ultimate transferable skill for someone in his position: behaviour management. During his years at the nightclub, he once had to ban a violent, drug- taking prostitute from entry. Her pimp then phoned him to complain. “I can’t run a business with people threatening other people with knives,” Bennett said. Fair enough, the pimp acknowledged. But it might be in Bennett’s best interests if he called the woman to offer her an explanation. “I had to phone a hooker on drugs and explain why she couldn’t come in,” Bennett says now. “It was surreal.”

Nonetheless, he goes on, “in my first year of teaching, I was very bad at behaviour management. It was a generally degrading experience. Night after night, I was going home and feeling that I was a failure.”

However, experience at the rougher edges of society can offer some useful lessons for facing down a class of recalcitrant teenagers. At the peak of his footballing career, Neville Southall - now a teacher of excluded teenagers - played in front of crowds of 100,000 people. When the Everton goalkeeper successfully saved a goal, the terraces at Wembley Stadium would break into chants of high-decibel approbation. When he failed to perform to standard, however, those same terraces would be united in equally vocal disapproval.

“If you’re playing a cup final, it can be watched by millions of people,” Southall says. “If you do well, everybody loves you. If you do badly, everybody hates you. I’ve had all sorts of things thrown at me. Half a brick, darts, golf clubs, a bag of grit. I’ve had abuse shouted, spitting. It just makes you want to go out and do the best you can next time.”

Bennett says, of his initial struggles with classroom management: “The only thing that kept me going was my experience in the club environment. I realised that, however stressed I was, I just had to stick with it. I’d been in that situation before.” He is now the TES in-house behaviour expert and author of The Behaviour Guru.

He also found that his previous work in clubs helped him to manage other elements of his new career. “In a nightclub, you have so many emergency situations. The power might cut out at the same time as there’s a fight and the fire alarm starts going off. Or you might run out of booze and bouncers at the same time. So you learn how to prioritise.”

Peel, similarly, found that his former career had bequeathed him unexpected classroom skills. He is now an English teacher at Slough Grammar School. “As a singer, what you have to do a great deal is analyse text,” he says. “You have to work out what’s going on and why. You’re interpreting poetry to the nth degree. So it was a different application of the same skill. You’re thinking about the ebb and flow of lines.”

And, while fellow teachers were struggling to make themselves heard or returning home hoarse, he had no such problems. “I have very good vocal control. I can be very loud, very quiet, in the middle. I never had problems with how to sustain my voice in the classroom. It’s a useful quirk.”

Useful quirks pop up in other career-changers’ conversations, too. Bennett points out that his former job “taught me how to take a punch. I can roll with a punch now.”

The value of failure

For others, however, the move into teaching was less about drawing on hard-won battlefield skills and more about forgetting everything they had ever known and starting all over again. Or, as they might put it in the army: breaking you down and building you up again in the right image.

Lynch is now vice-principal of the Springfields Academy, a special school in Wiltshire. The pupils have what he describes as “a cocktail of needs”, encompassing conditions such as autism and attention deficit hyperactivity disorder. “We have the usual: chair-chucking, attacking teachers, biting and spitting,” he says. “Children losing control of their emotions.”

But he can no longer meet violence with violence: there is no pinning children to the floor in a single move. “It’s just about responding to the children and meeting their needs. It’s about your professionalism. It’s not about being the alpha male. It’s not about being big and hard and I- can-deal-with-anything. It’s about being caring.”

It is also about recognising the value of failure. As a cadet, he wanted only success: if hesitation or injury meant failure, he was determined neither to hesitate nor to be injured. “Failure was not an option,” he says, without irony. In Northern Ireland, too, failure was unthinkable. “In that context, if you hesitated, then it could have a massive impact on others’ lives. You can end up with all sorts of casualties. These are times when you’re not allowed to fail.”

Now, however, he is an enthusiastic advocate for what can be gained through loss. “You’re not going to get there straight away,” he tells his pupils. “If you do get quick wins, you haven’t really earned it. Picking yourself up and dusting yourself off - that’s what life is all about.”

The value of failure is something that figurative - as well as literal, parachute-jumping - high-flyers are also keen to pass on to pupils. For the past six years, Southall has taught excluded teenagers in Kent and Surrey. “We try and get them to do everything,” he says. “Create an environment where you can make lots of mistakes, and it doesn’t matter. There’s no sportsman who hasn’t made mistakes. If you don’t have good days and bad days, how can you tell the difference?”

What Southall is known for, however, is his success: success of a very specific variety. “You turn into a little kid sometimes,” he says of his life as a professional footballer. “You’re driven everywhere. There’s always someone saying, `Let us take your bags.’ The only thing you have to do for yourself is wipe your bottom, really.”

But Southall joined Everton in 1981, when Premier League footballers were not yet paid the caviar-and-Cristal salaries they now receive. He earned considerably less than the tens of thousands of pounds a week enjoyed by today’s Premier League footballers, opting for long-term contracts over higher pay. Griffiths, too, points out that, even at the height of Harvey and the Wallbangers’ fame, when the band was earning around pound;1,000 a show, band members took home only about pound;30 each. The rest went to pay office staff, roadies and the show director. As a result, neither he nor Southall misses the ready cash of celebrity. “My salary went up when I became a teacher,” Griffiths says.

Both insist, similarly, that they harbour no lingering nostalgia for the screaming crowds and adulation of success. “The pupils aren’t wildly interested in the fact that I’ve been in a band,” Griffiths says. “I think their tastes are rather more hip than we were.” While in the band, however, he was invited on to the children’s television programme Playdays, to play the character of a string musician called Stringfellow. “The kids are really fascinated about that. Maybe they saw it when they were growing up. They’re not that curious about the band thing. But they always ask me about Stringfellow.”

Southall, meanwhile, does not tell his pupils about his cup-winning, Wembley-playing alter ego. “That was a previous life,” he says. “There’s no need to boast. It’s like going in and saying, `I was the best plumber in the world.’ I want them to judge me on what I do now. It’s up to you to make them respect you.”

When he left the operatic stage, Peel made a promise to himself never to sing in school. But he does admit to his past life: he takes his sixth- form tutor group to the opera each year and treats Year 13 leavers to a brief video clip.

“My tutor group ask, `How could you give that up? Everyone clapping you?’” he says. “My answer is, `Very easily.’ Everyone likes being clapped. That can be very nice, and there’s no pretending it isn’t. Nobody gives you a standing ovation as a teacher. You don’t get applauded out of the school gates.

“But singing is very transitory. Teaching is about building relationships with pupils and colleagues over years. Having children come into Year 7, and watching them grow into 18-year-olds. That’s something you don’t get elsewhere.”

Photo: Opera singer Jonathan Peel. Photo credit: Julian Anderson