Sixth-form colleges have been employing lecturers on fixed-term contracts rather than offering them full-time permanent jobs.
They have been cutting back on staff - recruiting fewer people despite the fact that greater numbers are leaving the sector.
Statistics from the Local Government Management Board reveal a 46 per cent increase in the number of fixed-term contracts offered in 1994. At the same time the number of part-timers fell by 15 per cent.
According to figures collected from 96 colleges, 89 people were offered fixed-term contracts in 1993. A year later 208 lecturers were on them.
The figures show turnover rates in sixth-form colleges rose by almost 1 per cent in 1993 to 7 per cent in 1994 - but the percentage was marginally less than in schools.
However, recruitment rates fell from 7 per cent to 6 per cent - almost 1 per cent lower than in schools.
The East Midlands was hit hardest by resignations (12 per cent), closely followed by Wales (10 per cent) and London (9 per cent). Lowest levels of lecturers leaving were in the South-east (6 per cent) and the South-west (6 per cent).
Male lecturers were more likely than women teachers to resign and accounted for more than half of those who left and nearly half of all those who resigned were aged 50 or over.
Almost half of the full-time teachers leaving were retirements - seven out of 10 prematurely - but just 6 per cent were vice-principals, 2 per cent principals and another 2 per cent other senior postholders.
The survey reveals that around two-fifths of the lecturers who resigned had fewer than two responsibility points, slightly under a fifth of them received two and about a third received three or more points.
It discloses that almost half of resigning teachers had spent nine years in their college, 10 per cent between six and nine years, 17 per cent between three and six and more than a quarter three years or less.
The main destinations - other than retirement - were other jobs in the local education authority sector and universities, higher and further education colleges. The number moving to other sixth-form colleges fell.
Recruitment was highest in Wales and the South-west (both 8 per cent) and London (7 per cent) and lowest in the West Midlands (4 per cent) and the North-west (5 per cent).
Jobs were more likely to go to women - more than half the recruits being female.
They were also likely to go to graduates aged under 30 and who were appointed to posts with one responsibility point or none.