The number of teachers working more than 51 hours a week has increased for the third year in a row, according to a new report.

And workload continues to be the major reason for teachers thinking about leaving the profession, according to the research by the Education Support charity.

Charity CEO Sinéad Mc Brearty said: “Staff workload continues to be a serious issue that directly affects the mental health and retention of talented education staff.

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“The type, not just the volume, of work matters. The least satisfying and most onerous administrative work is generally perceived to result from the accountability system. A review of the accountability system must consider the mental health and wellbeing of educators and pupils alongside educational outcomes.”

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In the research, the number of teachers who said they worked, on average, more than 51 hours a week rose to 37 per cent this year compared with 33 per cent in 2019 and 32 per cent in 2018.

And a total of 68 per cent said the volume of workload was a “major reason” for considering leaving the profession, compared with 71 per cent in 2019 and 72 per cent in 2018.

Half said dealing with unnecessary paperwork and data gathering was a specific reason for considering leaving (compared with 40 per cent in 2019).

The research also found that teacher stress levels are ‘rocketing’ under the coronavirus pandemic and that more than half of teachers have been suffering insomnia this year.

Geoff Barton, general secretary of the Association of School and College Leaders, said: “Schools have been underfunded by the government for several years without any let up in workload or an eye-watering level of accountability.

“It is an inherently stressful situation and sadly it is not surprising to see this reflected in an increase in signs of poor mental health.

“Neither is it a surprise to see that stress levels have intensified since schools reopened fully in September. Schools have been required to manage a complex set of Covid safety protocols while delivering education and catch-up support amidst rising levels of disruption caused by the pandemic.

“The situation is unsustainable in every sense, including in terms of the mental health of school leaders and their staff.”

The charity’s research was carried out in July by YouGov using a representative sample of 3,034 education professionals across the UK, including teachers and senior leaders.

A Department for Education spokesperson said: “We have taken consistent action to address teacher workload and wellbeing and invested millions in mental health charities to support teachers. This includes a new £8 million training programme run by experts to tackle the impact of coronavirus on pupils, parents and staff.”