Each year about 12 teachers in a thousand face what are euphemistically known as "capability procedures". But heads are loath to initiate the process, fearing it will be long and stressful.
Research for the Department for Education and Skills by the University of Manchester suggests that nearly half of the problem cases are tackled without resorting to official procedures.
One in five of these teachers is helped to overcome their problems. Two in five resign. Ill health or a job move account for the rest.
But once official procedures have been started an exit from the school or profession is even more likely. Only one in eight survives.
"Best Practice in Undertaking Teacher Capability Procedures" is on the DFES website at www.dfes.gov.ukresearchdatauploadfiles RB312.PDF Email Sam Saunders at J.P.Saunders@leeds.ac.uk