Tests to be taken by children in their final year of primary school pose the same stress risk as the 11-plus exam, as pupils who do not make the grade often consider themselves a failure.

The House of Commons Education select committee was told how working class boys, in particular, were among the most likely to succumb to this.

MPs were warned that 40 per cent of those who currently fail to reach the expected standard for their age may lose motivation and become disaffected.

However the possibility that Swindon's primary school pupils, and working class boys in particular, are disaffected was countered by Graham Steven, a teacher at Lawn Junior School.

"I would say that the average pupil sees the SATs as a challenge," he said.

"While a small number of pupils may show a lack of motivation, this is generally because they don't like the written tests and not because they are disaffected.

"We make sure the kids know that the ongoing teacher assessment is just as valid and is a better guide of their ability."

Alan Howe, English director of the Key Stage 3 National strategy, who lives in Swindon, added further weight to the idea that the tests ought not to be regarded as another form of the 11-plus. The end of Key Stage 2 tests are not a pass or fail scenario.

"They are totally unlike the 11-plus in that they don't lead to pre-determined pathways post primary school. Different children progress at different rates," he said.

"Good secondary schools build on the information that the tests provide to ensure that pupils of all abilities are taught well and are set the right level of work."

David Bell, Ofsted's chief inspector, also defended the tests saying that they enable children to make an effective start at secondary school.