The Year 5 class looked bemused. Standing in front of them was the Wicked Uncle from Babes in the Wood. They’d all seen him in menacing mode on stage at the Theatre Royal, Wakefield, and now here he was saying he’d come to be their supply teacher.

This incident, which happened a couple of years ago, is the kind Roger Butcher relishes. “When they realised who I was they wanted to know all about the theatre - and it’s part of my mission to interest them in drama and theatre,” he says. Mr Butcher knows how to do just that, because he is a professional teacher. A headteacher, in fact. His first career was in schools and he still enjoys returning to them, sometimes for a day’s supply every week while he’s on tour.

For some months art has been imitating life, in that Roger Butcher has been touring the country as Tom Duncan, headteacher, in Hull Truck Theatre’s production of John Godber’s Thick as a Brick. “He’s the head of a failing school, looking at the bottom of the league tables,” says Roger Butcher. “It rings true, because the research has been meticulous. John Godber keeps up with educational thinking, so when there are teachers in the audience, lots of bells ring. Mention Ofsted and there is either a stunned silence or a groan.”

And does Tom Duncan’s style of headship resemble Roger Butcher’s? “He’s a little bit dyed in the wool. I hope I wasn’t like that.” Now 55, Mr Butcher had plenty of time to develop a style: he was a teacher for nearly 30 years, including 13 as a head, at three Sheffield junior and middle schools, until he took early retirement in 1997. He’d always been a keen amateur actor but had decided on a more secure career when he married.

It was while he was at Southey Green junior school that he decided he no longer needed that security. The pension rules were about to be tightened up, and “it flitted across my mind then that I was seeing a door close on early retirement and I should grab the handle before it slammed shut”. His wife, also a teacher, said if he didn’t do it now, h never would. So he did.

Having been “governed by bells for 30 years”, Roger Butcher decided to find a theatrical agent. “I thought, naively, I’d just ring somebody up and that would be it.” But it wasn’t quite that simple. Eventually, he met someone whose mother played tennis with an agent and he made an appointment just to get some advice. When he went along for the interview, the agent was enthusiastic. “She didn’t have anyone on her books who was six foot three, quite big with a bald head,” says Mr Butcher. “She came to see me in John Godber’s Happy Families at Rotherham Civic Theatre and I joined her immediately. Fortunately, apart from two months straight supply teaching in early summer 1999, I’ve worked pretty solidly. I’ve done radio, panto, television, corporate video and this is the third theatre tour I’ve been on. Of course, I realise it may all dry up.”

Has he any regrets? “I enjoyed teaching - still do - and the career move was a positive one towards acting, not a negative one against teaching, but I was getting towards the end of my career and enthusiasm was beginning to diminish. I liked working with children, but since local management of schools was introduced in 1988, developments have taken heads away from the shop floor and my teaching had diminished. So, although I’d always wanted to be a head, I was glad to get away from the problems.”

The role of Tom Duncan allows him to explore some of the questions that would have been occupying him if he was still teaching. “There are debates about what an aspiring teacher can do, about the arts versus science and finding a balance in the national curriculum. By the end Tom realises he can fly the flag for the school.”

One thing Roger Butcher especially enjoyed in school was taking assembly - “the chance to perform” - experience which has helped him respond to audiences in his new profession. “Every venue, every audience is different. There are always new ways of doing things. And I still enjoy listening to the education debate when I’m not on stage.”

Teachers still have a chance to see whether Roger Butcher (Tom) speaks their language. Thick as a Brick is at the Greenwich Theatre between January 23 and February 3. Tickets: 020 8858 7755