Next week’s national industrial action marks a coming of age for teaching assistants and other school support staff. Ten years ago there were 61,000 teaching assistants in England, mostly women. They cleaned paint pots, helped struggling children with reading and maths and took pupils to the toilet.

Now there are 177,000 full-time equivalent assistants, of varying grades, doing everything from photocopying to taking whole classes. There are about 500,000 full- and part-time support staff in schools, including technicians, librarians, site managers, administrative and pastoral care workers, cleaners, caterers and dinner supervisors.

This marks a basic shift in the composition of the workforce. The figure is similar to the 500,000 or so full- and part-time teachers. And next week’s planned two-day strike shows support staff are not afraid to flex their muscles.

That strength relies not just on numbers but in the changed relationships between support staff, schools and teachers. Research shows their growing numbers and widening remits have, in many ways, made teachers’ lives easier.

Heads struggling with a high teacher turnover find that employing people from the local community in support roles can give children stability. This ubiquity can cause tension: supply teachers have complained that cheap cover supervisors are taking their work. But it is hard to see how schools could now function without support staff.

Union organisation and membership of support staff have also risen in the past 10 to 15 years. This has given Unison, their main union, reason to be bullish about its strike, planned for Wednesday and Thursday, over the latest 2.45 per cent local government pay deal.

“Support staff were once a peripheral group, dispersed and isolated,” said Dr Howard Stevenson, deputy director of the Centre for Educational Research at Lincoln University. “The strike will be an interesting acid test as to the extent to which they are emerging as a body with a collective identity.”

The response to Unison’s strike ballot was just 27 per cent, and it is unknown how many of its 200,000 school-based members will give up two days’ pay. If they all heed the strike call and turn up for picket duty, they have the clout to cause significant disruption.

Unite, Britain’s biggest union, which also has 20,000 members based in schools, also voted to strike. Up to 670,000 local government staff belonging to Unison and Unite could take part in wider action in local authorities across England, Wales and Northern Ireland. Key services such as refuse collection could be hit.

For some of the lowest paid support staff, the discontent is simple. At pound;6 an hour, the starting rate of pay in local government is the lowest in the public sector, but it is more than the pound;5.52 an hour minimum wage. Unison has called for a pay rise of 6 per cent, or 50p per hour, whichever is greater.

The situation for classroom assistants is slightly more complex. The average full-time assistant earns just pound;11,000 a year, and many bring their pay up to a living wage with family tax credits and child benefit. Even higher-level teaching assistants, who have more training and experience, can be employed on “split contracts”, only earning at a higher rate when actually doing “higher level” work.

Many assistants are also only paid in term time, meaning they are only paid for 38 to 44 weeks a year.

But heads say that even if high numbers chose to strike next week, the timing - so close to the end of the school year - means it could have less impact than it might.

Dennis Richards, head of St Aidan’s High in Harrogate, North Yorkshire, said: “It is the last week of term. Year 10 is on work experience, Years 11, 12 and 13 are gone and the others are on activities week. The striking support staff would be missing out on the school production and a trip to Flamingo Land.”

Tony Travers, a local government funding expert at the London School of Economics, said that the economic climate meant it was the wrong time to be challenging pay deals. “The difficulty is that none of the political parties is willing to talk about putting up public expenditure except at the margins,” he said.

“Any pay increase would mean a reduction in staff employed as there is simply not the money. We are on the verge of zero growth, possibly a recession, so however justified their claim, now is not the time to be pushing the case hard.”

THE AUXILIARY ARMY

There are now 326,400 full-time equivalent support staff in schools, but because so many are part-time, there are more than 500,000 people working in roles such as:

Teaching assistant

Welfare assistant

ICT, science and other technicians

Learning mentor

Librarian

Administrative staff, including secretary, school business manager and bursar

Personnel manager

Finance officer

Site manager and ground staff

Cleaner

Dinner supervisor

Catering staff (about 40 per cent employed by private companies)

Crossing wardens.