Teacher shortages may be blamed on many factors, including low pay, high-cost housing and fear of tough inner-city schools. Travel to work isn't usually mentioned but figures show that, when it comes to job-hunting, most teachers don't go far from home. The home-work radius is generally no more than 10 miles.
It is perhaps not surprising that experienced teachers, with a mortgage and children in local schools, are reluctant to move far. But the tight radius seems to apply to newly qualified teachers too. The evidence suggests that they apply for jobs very close to their training centre.
Alistair Ross, of the University of North London, is co-author of the report Teacher Supply and Retention in London, which found that half an hour is all that most classroom teachers in the capital were willing to spend travelling. "You can't get very far in London in that time," he says.
National Union of Teacher figures show a national total of 11.3 per cent of full-time primary teaching posts are vacant, of which 48.8 per cent are classed as difficult to fill, and 9 per cent of secondary posts, of which 49.5 per cent are hard to fill. The regions experiencing most difficulty in filling posts are inner London (86.3 per cent of unfilled posts are hard to fill), the East Midlands (56.8 per cent), the North West (55 per cent) and the South East (54 per cent).
'There's a remarkable lack of mobility in terms of where people train and where they teach," says Mr Ross. "Forty per cent of those we surveyed were working within 15km of where they trained.
'There's a preponderance of training places in the south-west quadrant of London, with Roehampton, Brunel, Kingston and St Mary's. That seems o have its effect on teacher shortages. They tend to be in the north and east of London rather than the south and west. The borough of Hammersmith and Fulham is 4km from Roehampton and 17.1 per cent of its teachers come from there.
"We found that London-trained NQTs applying for jobs in the capital put travel-to-work time very high on their list of considerations. Those coming to London from outside put it much lower."
However, teacher trainees in the provinces often have a negative view of London, seeing it as intimidating and expensive, with poor housing and tough schools.
Scott Swinton, of the Teacher Training Agency, says: "Mature entrants are much less likely to move because they have already put down roots. The same applies to entrants from the ethnic minorities, who often have strong ties with their community and family, and tend to be older too.
"PGCE students tend to chose a training centre near the university where they are graduating and by the time job-hunting comes around they are more settled.
"Of course, lower cost-of-living areas are always more attractive."
School leavers now generally are staying closer to home for their undergraduate years, setting the pattern for reduced teacher mobility. Whereas graduates who choose highly paid careers are likely to benefit financially from being willing to move anywhere for a job, the pay scales in teaching, with their limited variation, are less of an incentive.
Measures designed to encourage trainees to move to areas of the greatest need include on-the-job training with direct entry and a salary, cutting out the impoverished college year. But TTA figures show that only 304 trainees have started this year on the employment-based route. The six to 12 week refresher courses for returners now attracts pound;150 a week in London, the equivalent of the pound;6,000-a-year training grant.