Education secretary Ruth Kelly will today reject Mike Tomlinson's plans to replace GCSEs and A Levels with a new diploma to boost achievement and staying-on rates.

Her predecessor, Charles Clarke, appointed the former chief inspector of schools in 2002 to develop a blueprint for transforming secondary education.

Kelly will insist on retaining the "gold standard" of A Levels and GCSEs, while promising to boost the standing of vocational qualifications.

Tomlinson said he would be very upset if his plans were not taken forward.

A Levels were now "strangling both teacher and student scholarship", he said. 

Meanwhile, nearly 50 per cent of boys and a third of girls leave primary school unable to write properly, according to a report published yesterday by Ofsted.

The education watchdog said poor teaching was to blame and added that one in three English lessons were only satisfactory.

Tim Collins, the shadow education secretary, said: "The fact that at least one in three primary pupils go on to their senior school without being able to write properly is one of the single biggest failings of eight years of Labour government."