Primary school headteachers rate theft as a more serious offence than alcohol-related violence when considering applicants from teachers who declare a criminal conviction.

Around 70 per cent of primary heads would not even consider shortlisting an applicant with a conviction for theft, and the rest would want to know more before deciding. Only 40 to 50 per cent take the same strong line with drink-related violence, the rest being willing to take circumstances into account.

My survey of 200 primary and secondary schools in London and Yorkshire sought reactions to offences that a minority of teacher-training students come to us with: drink-related violence, such as assault in a pub; theft of clothing or driving away without paying for petrol; a minor drug offence; and speeding.

The Department for Education and Employment, which maintains a register of qualified teachers barred from teaching, is little help on any but the most serious offences - where no assistance is needed. Its standard response is that casesmust be considered individually.

For some years, we have advised successful applicants who have criminal convictions that some schools will reject them, but without being sure where schools draw the line.

Judging by my survey, secondary heads are generally more tolerant. Only 30 to 40 per cent said they would refuse to consider a person with a single conviction for theft, while about 25 per cent ruled out those with a conviction for drink-related violence.

Possession of cannabis is taken by primary heads to be no more serious than drink-related assault (40 per cent refusing to consider such applicants).

Fewer than 20 per cent of secondary heads regard a minor drug conviction as totally unacceptable. Surveys have found that around one pupil in three has tried cannabis by the age of 16.

London schools are slightly more tolerant of all offences than Yorkshire schools and more willing to consider mitigating circumstances.

The main difference is over drugs: up to one in five London secondary heads regards a minor drug offence as irrelevant, and London primary heads are almost as tolerant. In Yorkshire, those not ruling drug-offenders out altogether want to know of mitigating circumstances.

Would-be teachers with convictions for speeding can relax. Not one secondary head ruled out speeders altogether and two-thirds thought speeding irrelevant.

However, some remarked that they would not let such offenders drive the school bus. One remarked that since most people break speed limits without being detected, to acquire convictions suggests a seriously irresponsible driver.

It is likely that heads are more tolerant in practice than they claim to be on paper: we often act more reasonably than we say we will. However, my survey suggests that anyone with a conviction for anything more serious than speeding will find up to three in four primary schools and one in three secondaries closed to them.

So, what advice can be offered to applicants who have committed minor offences? First, don’t disclose anything until you are asked to: if you really are a reformed and decent person, you will have had a chance to make an impression before the conviction comes up. Second, when it does, be honest, stress the time that has passed, and that you have learned your lesson.

Mick McManus is principal lecturer at the School of Education, Leeds Metropolitan University