Schools will no longer be classified as “satisfactory” by inspections, under plans outlined by Ofsted chief Sir Michael Wilshaw.

Sir Michael said the term should be replaced with “requires improvement” as the current rating “covers a multitude of sins”.

“If you listen to what previous chief inspectors have said when they’ve produced their annual report, they say things like satisfactory is not good enough, the quality of teaching in satisfactory schools is not good enough, the progress of children in satisfactory schools is not good enough, and I think we need to be straight with parents, and honest with them, and say that satisfactory is a false designation,” he told BBC Radio 4’s Today programme on Tuesday morning.

His plans were backed by the David Cameron who said in a statement that the change marked a “massive shift in attitude.”

"I don’t want the word ‘satisfactory’ to exist in our education system. “Just good enough” is frankly not good enough. Every teacher, every head and every school should be aiming for excellence – no lower.”

"These words are being backed by action. Schools that ‘require improvement’ will be re-inspected within 12-18 months – instead of the three-year break between inspections they’ve had in recent years.”

Under the plans schools can only be classified as requiring improvement twice, or will be placed in special measures.

"Be in no doubt: this is a government that is incredibly ambitious for all the children in our country – and we will fight for them to get the best start in life,” the prime minister said.

But NUT head  Christine Blower said the change was “derogatory and insulting to pupils, teachers, school leaders and governers.”

“The government’s real agenda behind this change is of course inventing yet another category of schools that it will then seek to force into academy status.

“It is a pity that tomorrow’s Downing Street summit is not discussing what measures the government should be putting in place to support schools at a time when local authority and school budgets, along with capital spending on schools, are being cut.

“The government’s focus should be on identifying and providing the resources that schools need to provide the best possible education for all children. To be constantly changing the goal posts for measuring a school’s success is destabilising and demoralising for the whole school community”.