Teachers can be their own worst enemies. They are among the most respected professionals in society. Yet they threaten that respect by straining public credulity over their working hours.

Union leaders have suggested that teachers work 50-plus hours every week of the year. They imagined the public wouldn’t notice the length of the holidays.

The PricewaterhouseCoopers report may have been a statement of the obvious: teachers work harder in term-time than other professions, but make up for it with long holidays. However, the obvious needed to be stated.

The fuss about hours did nothing to advance the teachers’ cause - and not just with parents. Campaigns to recruit new teachers were drowned out by complaints about workload, followed by complaints that too few were entering teaching. It is a miracle applications have risen so much.

The Scots mistakenly set statutory hours limits. Such limits penalise efficient teachers and reward the inept. They may also create new teacher shortages. So I agree with Bethan Marshall that it is more relevant to ask what teachers are doing with their time than how many hours they work.

By their own account, primary teachers last year taught or supervised pupils for 25 hours a week. A further 15 hours was spent on lesson plans and marking exams and homework. In part, this reflected the literacy and numeracy strategies. As lesson plans will be re-used, that figure may be an overestimate. But while some schools expect too much record-keeping, most of the work is essential.

Nearly nine hours is spent on administrative tasks (aside from lesson-planning and pupil record-keeping), including three hours “setting up or tidying up” classrooms. It is here that change can best occur. PwC highlights reasons for the variations in workload between different schools, such as the reluctance of some heads to hire administrative staff and differences in hours spent at meetings.

If the unions want to reduce working time, they should focus their efforts here rather than on pretending that teachers work harder than the rest of us.

Cutting out meaningless meetings would certainly reduce the hours “worked”. Ring-fenced funding for extra administrative staff should be introduced. Unless it is ring-fenced, heads will spend it elsewhere. Heads then need to organise support staff timetables better - with early shifts for admin staff to help with photocopying.

Heads and senior teachers often work longer hours than comparable professionals. They must have proper support to do their job and computers can greatly reduce the time spent on pointless paperwork.

However, if teachers are to keep public support, their time must be seen to be well-used. The school day should be for teaching. Training in teaching time has created a “shortage” of supply teachers and led to “four-day weeks”, despite there being four supply teachers for every vacancy. The five training days should also be properly used. And teachers should be paid for training at other times.

Of course, exam boards and the Office for Standards in Education can do better. There was too much material sent to schools and some found it hard to filter essential guidance from good practice guides. Preparation time for inspections can be cut and targets better focused.

But PricewaterhouseCoopers show that the biggest changes must come in schools themselves. Since they have brought a welcome honesty into this debate, the unions may have unwittingly performed a public service in persuading the Government that such a review was needed.

Teachers should work with the Government to embrace the sensible reforms proposed. Teachers might be surprised at how much public support their stance then enjoys.

Conor Ryan was special adviser to David Blunkett, 1997-2001 Talkback, page 23