By contrast, say the inspectors, only one in 12 lessons taught by NQTs in secondary schools and one in 20 in primaries was graded as unsatisfactory or poor. The small percentage of poor primary NQT lessons comes despite the rise in the one-year postgraduate certificate in education course and the decline of longer undergraduate courses. The PGCE route is now the main source of primary NQTs. Some see this course as too intense and condensed but it does not seem to be affecting the quality of teaching.

The NQTs in this survey were the first to have received the pound;6,000 training grant that has done so much to boost secondary recruitment. As the effects of that are felt over the next few years it is to be hoped that the percentage of poor secondary NQT lessons will drop to that in primaries.

One pointer is that inspectors witnessed even fewer poor lessons from primary trainees than from NQTs: just 3 per cent compared with 5 per cent.

In secondary schools, 8 per cent of lessons by both trainees and NQTs were poor but a higher proportion of trainees’ lessons were excellent or very good (15 per cent compared to NQTs’ 10 per cent).

Nevertheless, there seems to be no substitute for experience. Around a quarter of all lessons taught by qualified teachers of more than one year’s service were judged excellent or very good.

Sadly, lessons taught by supply teachers were seen to be of poorer quality, with 15 per cent of their secondary lessons being poor or unsatisfactory.

There were particular problems when these teachers taught outside their own disciplines.

However, with more and better- trained NQTs set to enter schools over the next few years, the negative effects of these short-term supply teachers may become a distant folk memory.

John Howson is director of Education Data Surveys