Falling rolls are having a noticeable impact on the number of teachers employed in secondary schools. The January 2009 census by the Department for Children, Schools and Families revealed the lowest number of qualified regular teachers employed in secondary schools since 2003, at 201,800.

The fall in the overall number of teachers, including trainees, overseas teachers and supply teachers, was less marked, at the 215,900 quoted above.

The number of qualified regular teachers - who probably add the most value to pupils’ learning - was just 93.4 per cent of the teaching force, compared with 96.8 per cent when Labour came to power in 1997.

Over the past year, there has been a small increase in the number of instructors and overseas-trained teachers, up by about 100 to 6,900. Meanwhile, employment-based trainee numbers fell by about 300 to 3,100, the lowest level since 2003. Training and Development Agency for Schools plans will probably result in further falls. There are still far fewer occasional teachers in secondary schools than in primaries. On the day of this year’s census, there were some 4,100, compared with 4,600 last year.

There are more part-time teachers than in the recent past. This year, the equivalent of more than 20,000 full-time teachers were working part-time in secondary schools, compared with just over 13,000 in 1997. In practice, more than 34,000 teachers were working part-time, which is about 16 per cent of the teaching workforce.

Part-time teachers are much less common in the north of England than in the south. Schools in London and the South East employed nearly 10,000 part-time teachers

John Howson is a director of Education Data Surveys, part of TSL Education.