Working-class communities can lack the "aspiration and drive" seen in many migrant groups, according to Ofsted chief inspector.

Amanda Spielman suggested there had been a "long overdue debate" about why white working-class children were falling behind, and the nation was having to deal with the "unhappy fact" that many communities had felt "the full brunt of economic dislocation in recent years".

In a speech to the Festival of Education at Wellington College, Berkshire, Ms Spielman said analysis showed schools in some areas of England faced real challenges.

But she added that it was Ofsted's job to "report without fear or favour" on school performance, and that while some schools had a harder job to do than others, they were graded on their overall standards not their "effort".

Ms Spielman told the festival: "We can't pretend that Ofsted judgments are not lower in certain areas - many of them with a high proportion of white working-class children.

"But that shouldn't surprise us. Over the past few years, there has been a long overdue debate about white working-class communities in England, and why they have fallen behind.

"That debate hasn't been limited to the UK and our coastal towns. It has also echoed throughout continental Europe and across the Atlantic.

"We are having to grapple with the unhappy fact that many local working-class communities have felt the full brunt of economic dislocation in recent years, and, perhaps as a result, can lack the aspiration and drive seen in many migrant communities."

Government analysis shows that schools in these areas "face challenges in terms of their pupil intake, and that there are also real capacity issues", she said.

They can struggle with teacher recruitment, fewer local academy sponsors and less access to support for leadership.

"Our job, is to report without fear or favour on the quality of education as we see it in these areas," the Ofsted chief said.

"That is explicitly not the same as saying that teachers in these areas are putting in any less effort or that the leadership is worse.

"There is no doubt that these schools have a harder job to do than others. And we should be just as interested in why some schools in more affluent areas aren't doing better. I have nothing but admiration for the teachers who make it their mission to tackle disadvantage.

"But the overall effectiveness of a school is not an effort grade.

"However, that is not the same as the inspectorate being biased against certain schools. What our inspection outcomes do is to act as a call for action in these areas - a call for the right kind of support and intervention."

Earlier, Ms Spielman's predecessor, Sir Michael Wilshaw suggested that London schools performed well because many immigrant families "care about education".

"The reason why London schools are doing so well, apart from good headteachers and teachers, is that a lot of the immigrant families care about education, they value education, they support their children," he said.

"I'm working in parts of England with white British populations where parents don't care. Or a lot of them don't care. And the headteachers tell me that less than 50% turn up to parents' evening. Now that's outrageous."

Ms Spielman also used her speech to confirm that Ofsted would not be ditching the current grading system - which sees schools rated as outstanding, good, requires improvement or inadequate - at this point.

"I know that there are some who would like Ofsted to abandon grades altogether or to move to a pass/fail model," she said.

"For me, that is a decision which must squarely be decided on the basis of whether the current grading system meets our mission of being a force for improvement. We will keep this under regular review.

"But we've concluded, on balance, that it is right to maintain the current grading system in the new framework."

Teachers and parents prefer the current system, she said.

But she did call for rules exempting outstanding schools from regular inspections to be changed.

"If we are to keep the grading system, I have to be sure that people can have confidence in grades," she said.

"That is why I would like to see the removal of the outstanding exemption. I entirely understand why the exemption was brought in. My starting point is always that we should trust our best leaders and teachers to get on with the job.

"But there are now almost 300 schools that have gone a decade or more without inspection. And regardless of what the quality of education in these schools is today, there is no doubt that the long gap since inspection has undermined parental confidence."