Teachers are shunning headships because they are better off in the classroom it was claimed this week, as contradictory figures on headteacher recruitment in Wales were published.
John Evans, president of the National Association of Head Teachers (NAHT) Cymru, said a lack of aspiring heads in Wales was down to poor pay rises on promotion. He also claimed some of the best candidates for the job were being turned down for the National Professional Qualification for Headship (NPQH), now a requirement for all first-time headteachers.
It comes as new research suggests Wales is not tackling head recruitment effectively enough.
The 12th annual survey by Education Data Surveys, an Oxford-based research company, suggests secondary head recruitment is improving, except in Wales.
Just nine Welsh secondaries responded to the survey, but they received an average eight applications for headships in 2005-6, compared with 16 for England and Wales, and as many as 25 for schools in south-east England.
The situation in both Welsh and English primary schools worsened, with three out of 10 head posts unfilled, and applications down from an average 5.4 to 4.8.
However, Wales now has the highest proportion of primary heads aged 35 or under (18 per cent). Three-quarters are women.
Dr John Howson, who produced the report for NAHT and the Association of School and College Leaders, tracked nearly 3,000 leadership jobs advertised in the past year.
He said: "The Assembly government appears to have thought of it but has no firm plans to tackle a fast-approaching recruitment crisis in headship."
However, Assembly government statistics published last week show Welsh secondaries received an average 22 applications for 10 head or deputy vacancies advertised in 2005, up from 21.5 the previous year.
There were no figures for primary leadership posts.
An Assembly government spokesperson said it had taken into account a predicted increase in headship turnover by 2010 in work on the NPQH.
"We are developing a healthy pool of qualified heads. Almost 900 practitioners have successfully gained the NPQH. It is predicted that up to 1,700 will hold the qualification by 2010."
John Evans, who has been head of Marlborough Road junior school, Cardiff, for 20 years, said the findings confirmed his fears that there were not enough aspiring heads to "fill old shoes".
Figures released by the General Teaching Council for Wales in March show Wales has an ageing population of heads, with more than 65 per cent over 50.
Mr Evans said: "If teachers are happy in the classroom they may see an extra couple of thousand for a headship as just not worth it. There is already a backlash from teachers who do not want managerial tasks."
Fears of a crippling shortage of school leaders in England are being fuelled by the record numbers of teachers quitting the profession. In Wales in 2005, 492 teachers took early retirement or left to work outside the profession.
But figures for England from the Department for Education and Skills show that 14,000 teachers quit last year - the highest number since New Labour came to power.
The figures lend weight to a survey, published by England's GTC, which indicated that 37 per cent of teachers felt they would quit in the next five years.
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