At last, I thought, a blow has been struck for schools. Somewhere a head has dared to say no to the teacherexaminer’s request for time out of school to do examining business. They should have held the meeting on a Saturday - I wonder how many teachers would have wanted to attend then?

The head draws attention to one of the biggest problems bedevilling the examination system: it depends on serving teachers. By definition, serving teachers have a day job that they are paid to do. If their examining work impinges too much, their school work will suffer. It’s unavoidable. And unacceptable.

Can you imagine a teacher moonlighting as a barmaid - a legitimate use of her free time when school is shut - and asking for days off to train others to be barmaids or to pick up the tricks of the trade herself?

Wonderful though some supply teachers are, they are hard to find, especially for schools in the inner city, or so far into rural England that distance defeats them. At best, they are caretakers, while possibly some of your best teachers are off on examining - or barmaiding - business.

The analogy is not as silly as it sounds for pupils, or for colleagues who get roped in to cover. The reason for absence doesn’t matter. Their regular teacher is not there. Period.

There are two arguments for allowing or encouraging staff to become examiners: first, they will become better teachers of exam groups; second, it equips them to work as examiners when they retire - which is a nice little earner. Less commonly cited is that examining can offer a career path in its own right, an escape from classroom stresses.

Personal experience tells me the first argument is true. I’ve marked for key stage 3, for GCSE, for old GCE and CSE, and for A-level. The heads I’ve worked for always set a limit on the amount I could do; after all, the gain in expertise does not necessarily increase with each year of examining.

It’s not just days off that can be an irritant. Exams in mid-May are likely to need prompt marking in batches of up to 300 papers in about three weeks.

Fine if you’re retired or on a career break, but how do you cope with a demanding day in the classroom when you’re exhausted by four and five-hour marking stints? Would you want to be working as an examiner in the week your school was being inspected? If the answer is no, point made.

Exam boards have never been more accountable, so they want serving - and experienced - teachers. Their demands, and possibly enticements, will increase so they can satisfy their need. But, at the same time, schools are accountable for every lesson of every day. Pupils should not be losing the committed service of good teachers because the exam boards have a problem recruiting staff, and paying schools for supply staff will not cure the problem.

Maybe the answer is to close schools for a week and draft all teachers into examining work. Exam boards can claim all the teachers they need and pupils’ work will not be affected.

Meanwhile, three cheers for the head who told the principal examiner that being in school on a week day was more important than feeding back exam information to teachers. He has put down a marker for all of us.

Sue Roberts is head of an independent girls’ school. She writes under a pseudonym