As if GCSE results weren’t complicated enough the government has again changed the way schools are ranked.

Last summer’s exams saw students graded from 1 to 9, instead of on the traditional alphabetical scale, for the second time.

The highest grade is 9 and equates to a result above the old A*, while 4 is the same as a C.

Schools get a score for attainment based on how well pupils do in eight subjects, with the national average for all schools currently 44.5 compared to 46.5 for state-funded schools. The maximum score is 90.

The Department for Education has added an additional measurement, which ranks pupils’ progress since leaving primary school in eight subjects.

The national average is presented as 0, with schools above 0.5 considered well above average and those below -0.5 well below the standard.

This year’s results show that, as in previous years, selective schools performed best.

Rochester Grammar School was top of the pile in terms of both ratings, with an attainment score of 66.6 and progress of 0.63, both well above average.

Thinking Schools Academy Trust, which runs the school, was rated in the top 10 nationally, with students improving on the predicted grades they were given at the end of primary school by a third.

Rochester Math came second with scores of 65.6 and 0.49.

At the other end of the scale Bradfields Academy, a special school, achieved 0.8 and -1.46.

Inspire Free Special School, in Churchill Avenue, Chatham, had a progress rating of -2.71, the lowest in Medway.

Tonbridge Grammar’s attainment rating of 77.9 made it the best performing school in Kent, while Weald of Kent Grammar (71.2) had the highest progress rating of 1.01.

Medway Council said the Towns were improving faster than the national rate — the district is now 77th in the country for English and maths, 34 places up from last year.

Cabinet member for children’s services Cllr Andrew Mackness (Con) said: “Although it’s encouraging that Medway’s results have improved, we recognise more can be done to ensure young people are provided the best possible opportunities.”

Education chief Cllr Martin Potter (Con) added: “I am pleased that Medway’s secondary schools continue to make good progress. The latest figures are promising and show that we are improving faster than the national rate for the number of children who received a standard pass in GCSE English and maths.

“I would like to congratulate our young people who work hard throughout their education and to all of the teachers, parents and guardians for the support they provide day-in-day out to ensure children have the best start in life. We are not complacent and we will continue to challenge schools to ensure that Medway’s results continue to improve.”