All 490 Essex primary heads are expected to attend a rally on January 28 to voice concerns that they will be unable to maintain standards and guarantee teachers 10 per cent planning, preparation and assessment (PPA) time from September, as part of the workload agreement.

Ruth Brock, executive chair of the Essex Primary Heads Association, said:

“The heads have made it clear that this is an issue that is not going to go away.”

But Mary Bousted, general secretary of the Association of Teachers and Lecturers, said: “To be organising rallies at this stage, just when the agreement is starting to impact on teachers, is highly irresponsible. Heads have had just over two years to plan for PPA time. It is about time they stopped whingeing and started planning.”

Jonathan Evans, head of Larkrise primary, Chelmsford, had to make cuts in staffing after a big fall in pupil numbers. When he arrived in September 2003, he took action to prevent the school incurring a pound;33,000 deficit on a pound;450,529 budget. One teacher was made redundant, teaching assistant hours were cut by a quarter, midday supervisors were cut from seven to five, and spending by subject leaders was put on hold.

But Mr Evans is worried that PPA time would cost pound;5,785 if teaching assistants covered lessons - something he is not prepared to allow on principle. The alternative, using extra teachers, would cost Pounds 14,500-pound;17,000 and put him back into deficit.

As the deadline approaches, more schools, particularly primaries, say they will not have the money to bring in the change.

And education authorities are also beginning to speak out. Martin Butcher, Bournemouth council’s remodelling adviser, told The TES that of 28 primary schools in his authority he knew of only one school that could even introduce 5 per cent PPA time.

Jon Mager, education director in the East Riding of Yorkshire, said he shared heads’ concerns. The deal had not been designed with rural schools in mind and 20 to 30 schools would have difficulty recruiting enough staff.

Richard Brock, Bath and North East Somerset assistant education director, said the authority estimated pound;500,000 would be needed, equivalent to an extra 1 per cent on council tax.