Bad news for complacent leafy suburbs
Mr Bell's promise to send inspectors back every 12 months to check on progress of such schools sends a clear message that unless they get their act together they face embarrassment in front of parents.
Suggesting they should be made to submit action plans to their local authority will only serves to rub salt into their wounds.
At first glance, it looks like a straightforward attack by the chief inspector on "coasting" middle-class schools who do well in the league tables but could do better.
But for better and for worse, this is one of those cases where the headline figures do not tell the full story.
First, the good news for schools: on closer inspection, it appears that the number requiring fresh action is relatively small.
Of the 1,000 schools improving too slowly about three-quarters (719) are already subject to intervention because they are in special measures, serious weaknesses or one of the other categories of concern.
These, by and large, are not coasting schools in middle class areas but schools in disadvantaged areas struggling with tough social problems and difficult intakes.
So does this mean Mr Bell believes there are only 280 schools requiring intervention? Are the overwhelming majority of surburban schools off the hook?
No. The figure of 1,000 schools represents just one in 10 of the schools inspected during the past three years. At the launch of his report Mr Bell made clear that he believes these figures can be extrapolated across all schools in England.
Taking the chief inspector at his word, that means there are 1,780 primaries and 340 secondaries guilty of not doing enough to improve.
When the schools already causing concern are removed, that leaves 1,400 schools which currently have a clean bill of health who face annual inspections and intervention by local authorities.
Ensuring that all schools do their best by every pupil, whatever their circumstances, is an admirable aim.
But there must at least be a suspicion that Mr Bell's figure of one in 10 schools needing intervention is an exaggeration.
After all, it seems obvious that schools already giving cause for concern are more likely to be making insufficient progress. If they are excluded from the calculation the number of schools not improving fast enough falls to one in 30.