Q: How big is the shortage?

A: A recent survey by justforteachers.co.uk, which gauges the satisfaction levels in the education world, revealed that more than three quarters of teachers in the North-East are considering quitting their jobs. A worrying aspect for the Government is the number of newly-qualified teachers who are quitting the profession within three to five years of qualifying. The survey, published earlier this month, revealed that already 22 per cent of new teachers wanted to leave.

Official figures published in April showed that vacancies almost doubled over the previous year to 4,690 - despite the fact that there was a net increase of 5,600 in the number of teachers to 410,300.

Mr Tomlinson's view that the problem is the worst it has been since 1965 carries a lot of weight, as his inspectors see what is happening in classrooms across the country on a daily basis.

What is not clear is how many teachers are taking lessons in subjects in which they do not specialise, a phenomenon known as ''mis-match''. While not a problem for primary schools, unions suspect the practice is widespread in comprehensives, as head teachers use all means at their disposal to avoid cutting the timetable. Unions argue that the use of non-specialists could mean that children are less well-prepared for national tests and GCSEs in the summer than they might have been.

The Government is supposed to carry out a survey of what teachers are actually teaching and to publish the results once every five years. The last was conducted in 1996-97 and a Department for Education and Skills spokeswoman said the next was ''not imminent''.

But the DfES said 91 per cent of lessons in maths - a particularly badly-affected subject - were taken by staff ''with a maths qualification''.

Mr Tomlinson said he expected to report an increase in mis-match in his next annual report, due out early next year.

Q: How did it happen?

A: Recruitment in state-run schools is a problem throughout the western world, made worse by almost a decade of economic growth. The private sector can pay graduates higher wages, which is particularly important given spiralling housing costs.

But Terry Bladen, a Darlington teacher and junior vice president of the National Association of Schoolmasters/Union of Women Teachers, says: "I know that in the south it's a lot to do with salary because people can't afford to buy houses. Up in this area people seem to say it's the problems with workload, they see friends who they went to university with who have basically got a life while they're spending every night and weekends working. The other factor is the problem with discipline in schools."

Newly-retired Darlington teacher Tony Dobson believes the exodus started when Tory Education Secretary Gillian Shepherd changed the rules on pensions. It meant teachers had to decide whether to retire at 50 or stay on until they were 60.

"Some of the comprehensives around Darlington lost a nucleus of experienced teachers who were replaced by newly-qualified teachers, who were in turn under a lot more pressure," says Tony, who taught at Branksome Comprehensive for 30 years. "A lot of people I knew who were 50 had to look at soldiering on until they were 60. A lot of those who left were heads of year with lots of experience. I've been the only teacher at my comprehensive to reach 60 - the others either retired or had breakdowns."

Q: Are we likely to see four day weeks in the North-East?

A: School standards minister Stephen Timms came under fire last month for saying it looked as if schools would have the teachers they need by September.

But unions say the teacher shortage crisis does not look like easing and will only be exacerbated when the flu season hits. Already the teacher supply agencies, who provide teachers to cover for sick leave and long term absences, are stretched to their limit.

Earlier this year, Paul McHugh, the headteacher of Easington Community School in County Durham, was forced to turn 200 pupils away - an entire year - when he could not get cover for sick staff.

Four-day weeks will also be a virtual certainty if the main teacher unions take industrial action in support of their demand for a 35-hour week. The National Union of Teachers, the National Association of Schoolmasters Union of Women Teachers, the Association of Teachers and Lecturers and Welsh union UCAC have all voted overwhelmingly in favour of holding ballots if the Government does not give in.

Nothing is likely to happen until the results of a review of teachers' workload being conducted by management consultants PricewaterhouseCoopers is completed in the autumn. But the Government knows that the NUT and NASUWT could also revive a separate, suspended work-to-rule if they are not happy with the outcome.

Even heads could get in on the act. The National Association of Head Teachers has threatened to take industrial action for the first time in its history in support of a demand for a set number of hours of ''management'' time off from classroom duties each week.

Q: Why can't we keep our newly-qualified teachers? Do they not know what to expect when they enter the profession?

A: The justforteachers.co.uk survey revealed that North-East teachers felt one of the hardest lessons to get across was respect. Many are disillusioned by the disruptive or violent pupils they come across on a day-to-day basis.

Mr Bladen says: "I think it's very much a culture shock for them. OK, they do teacher training and teaching practice, but actually that's for a fixed length of time and you can see an end to it. When you come in to school and it's going on day after day, month after month and the newly- qualified teachers see what their colleagues from university are working hard but at least they have a life, you can see why they're leaving."

Q: What is the Government doing to tackle the problem?

A: It has come up with a range of incentives. Graduates in so-called ''shortage subjects'', including maths and science, get £4,000 ''golden hellos''. Training salaries worth £6,000 are available to those studying for their post-graduate certificate of education.

Heads can now put good teachers up for £15,000 ''golden handcuffs'' payments after three years and undergraduates who chose to become teachers have their student loans paid. There is also a two-year £70m fund to help teachers with housing and childcare costs and a £2,000 ''welcome back'' bonus to tempt qualified teachers back into the profession.

Earlier this summer, it emerged that the bulk of a £250m initiative to help essential public sector workers with housing costs was to be directed at teachers. New staff can earn £17,000 outside London or £20,000 if they work in the capital, compared with the average graduate starting salary of £19,800.