Office staff in schools should be trained by the Government to handle the difficult, angry and sometimes irrelevant enquiries they receive from parents.

So say Nottingham university researchers who found that parents would sometimes call schools with complaints about matters entirely outside their control, such as litter, parking and neighbourhood squabbles.

One primary headteacher said that parents had blamed her when their children became muddy playing on a bark surface underneath the school’s new play equipment. “Parents were slinging school uniforms down and asking me if I was going to wash them,” she said.

School staff also reported that parents often failed to understand that teachers could not rush out of their lessons to talk to them on the telephone.

One secondary-school office manager, quoted anonymously in the Nottingham report, said: “They can’t seem to grasp that teachers are teaching all day.

They might have one period free, or they might not because they need to cover.

“They’re not available from half-past eight to half-past three. And that’s difficult because parents quite often say ‘Oh I rang this morning and you haven’t got back.’”

The researchers studied 10 schools in depth and heard accounts in each of them of inquiries from “challenging” parents. Office staff would often have to wait until a parent’s initial burst of anger had died down before they could discuss their concerns.

Although the study did not report that any staff had been attacked by parents, some said they had found their behaviour intimidating.

Parents of primary children tended to make enquiries in person and most wanted to discuss money-related matters such as payment for lunches and school trips.

In contrast, secondary-school parents preferred to contact schools by phone. Their chief reason for calling was to speak directly to an individual teacher or year head.

Staff at the oversubscribed schools studied by the researchers said they spent much of their time dealing with persistent calls from parents who wanted a place for their child.

The researchers said that the time headteachers and office staff spent answering these calls, which often concerned children who would never attend their schools, was a “hidden cost” of popularity.

The study concluded that the Department for Education and Skills should develop an online training scheme to help school office staff handle routine and challenging enquiries from parents.

An investigation into queries that school offices receive from parents and carers is at www.dfes.gov.uk