by political editor Paul Francis

Classroom standards at Kent’s secondary schools have improved yet again - but one school is among the worst in England.

School league tables published by the government indicate another year of improving standards, with students posting another set of record-breaking results.

But the Bishop of Rochester Academy, Chatham, had just 16% of pupils attaining the GCSE benchmark - the third-worst in England.

Medway's secondary school results

Alongside Kent's overall good results, there was some cause for concern based on results in the so-called English Baccalaureate, a new measure of performance.

And there was a big gap in the achievements of poorer pupils in their GCSEs compared with other children.

Overall in the county, six out of ten pupils achieved five or more good GCSEs at grades A* to C including English and maths, rising to 59.4% in 2011 compared with 57% in 2010.

That was marginally above the national average of 58.9%. All but 11 secondary schools passed the threshold of 35% of pupils securing five good GCSEs set by education secretary Michael Gove.

However, a new indicator showing how well pupils from disadvantaged backgrounds did compared with others revealed a significant gap.

Why are less well-off pupils in Kent so far behind?

For Kent, this revealed that pupils on free school meals are half as likely to get five or more good GCSEs than others. The tables show that 28% of disadvantaged children secured five GCSEs compared to 63% for others.

That is likely to cause concern among county education chiefs.

For the second year, the tables rate schools on the basis of the proportion of children obtaining the English baccalaureate.

This is awarded to those children who achieve English, maths, a science, a foreign language and a humanity such as history or geography.

The new measure is intended to reward schools that offer a broad but academic curriculum.

In Kent, one in five pupils passed the Baccalaureate and more than half - 66 of all schools - saw less than 10% of children achieve the new benchmark.

Of these, 29 of the schools saw no pupils at all reaching the level of the Baccalaureate.

While the county’s selective grammar schools came out top in terms of exam performance, non-selective schools did well in terms of their added value score. This measures the progress of pupils and takes into account deprivation factors.

The secondary school league tables - what's new?

The tables continue to show the number of pupils achieving five or more GCSEs at grades A* to C including maths and English as the main benchmark.

However, this year the tables also include a new indicator known as English Baccalaureate to measure performance.

This shows the number of pupils achieving five or more GCSEs at grades A*to C in core subjects. These are English, maths, one science, one foreign language and one humanity subject.

The tables also carry more detail about how well disadvantaged pupils are performing compared to others.

This is measured by looking at GCSE passes of those on free school meals or in care and comparing them with those who are not disadvantaged.

The value added measure in the tables is calculated by comparing each pupil’s best eight GCSEs and taking into account their different starting points and progress since arriving from primary school.

A score of 1,000 is the average so everything above that is regarded as adding value.