Headteachers have warned of an “exodus” from the teaching profession, as research indicates more than a quarter of schools were unable to fill senior posts last year.

A survey by heads’ union, the NAHT, has found 26 per cent of respondents failed to recruit to teaching posts on the upper pay scale in the 2013-14 academic year.

Some 24 per cent failed to recruit teachers on the main pay scale and 29 per cent failed to fill posts for teachers with additional responsibilities, known as Teaching and Learning Responsibilities (TLR).

The problem was less acute for those recruiting newly-qualified teachers, of which 8 per cent were unable to fill posts.

The survey of 1,178 school leaders found that the most common reason cited for struggling or failing to recruit teachers was that the quality of applicants was not good enough.

Just under 29 per cent said there were “plenty of applicants” but that they were “poor quality”.

The NAHT survey shows that the recruitment problems were most acute in London, the north of England and the south west, and that maths and English were the most difficult subjects in which to recruit.

A motion set to be discussed at the NAHT’s annual conference in Liverpool says there has been an “exodus” from the teaching profession. It says “unrealistic expectations” being placed on teachers must be tackled urgently to mitigate this, and that teachers must be given an “appropriate work-life balance”.

Louis Coiffait, chief executive of NAHT Edge, the union’s branch for teachers in middle-management roles, said: “It’s time to be frank; we’re facing a recruitment crisis at all stages of the education system.

“Until we address it at each of those stages, there’s no chance that we’ll have the quantity or quality of head teachers we need in the future.”