A third of all teachers plan to leave the profession in the next five years, a new poll has found.

Most have been driven out by excessive workloads and unreasonable managers, according to the YouGov survey of 796 teachers, ranging from the newly qualified to those with decades of experience.

The survey, conducted on behalf of the Teacher Support Network, found that 34 per cent of all teachers plan to leave the profession by 2020. And a further 22 per cent intend to quit their jobs within the next six to 20 years.

Only 10 per cent said that they were planning to remain in teaching for more than 20 years.

The results come amid what many schools are describing as a teacher recruitment crisis. The overall national vacancy rate has doubled in the last five years. Figures released this month show that increasing numbers of teachers are being asked to teach outside their areas of specialism, and schools are once again recruiting staff from overseas.

The YouGov poll found that 45 per cent of those planning to leave teaching cite retirement as a factor in their decision.

But 40 per cent claim that excessive workload is forcing them to leave profession. And 24 per cent say they are being driven out by unreasonable demands from managers.

A further 19 per cent say that pay and pensions are behind their decision to quit, and 18 per cent cite the rapid pace of organisational change.

Only 13 per cent say that student behaviour has motivated their departure, equal to the number of teachers who say that they simply want to work outside of education for a change.

Julian Stanley, chief executive of the Teacher Support Network, said: “If we are to stem the tide of departures, the culture in schools must change to proactively engage with teachers as highly competent professionals, who deserve a high level of respect, support and professional development. In short, we must love our teachers or lose them for ever.”

John Howson, of the University of Oxford’s education department, said that the situation would only be worsened by the 800,000 additional pupils due to enter the education system over the next decade.

“Schools and the government need to make sure that we keep as many teachers as possible in the profession,” he said. “We can’t afford to lose people.”