Ninety per cent of the pupils at the inner-city girls' school are from ethnic minorities and one in five is a refugee. For more than two-thirds of the pupils, English is not the first language, while an astonishing 38 languages, other than English, are spoken at the school. Almost a third of the girls have special needs while 72 per cent are entitled to free school meals.
Headteacher Cheryl Day is resigned to the annual production of school league tables which this year show that 22 per cent of girls at her school (down from 32 per cent the previous year) achieve five or more A to C grades at GCSE with an average points score of 29.5.
"In terms of the national picture," said Ms Day, "It's fair to say we don't appear right at the top."
But the school, which in recent years won a battle to retain the single-sex status it has enjoyed for nearly a century, was happy to participate in the value-added pilot scheme, involving 200 schools.
Clapton excelled, receiving an A-grade with an overall value-added mark of +6.1 per cent.
The value-added pilot scheme allows a fuller picture to be painted of a school's performance, explained Ms Day. Deputy headteacher Stuart Phillips was quick to add: "We would not want to make the socio-economic background an excuse for failure. We are looking to challenge all our girls to reach the highest potential of their education."
Ms Day said: "I do welcome the Department for Education and Employment trying to establish a way of measuring what value the school has added. What our school adds is considerable. The staff work extremely hard to produce excellent results and if this is a way of acknowledging that then it's excellent.
"The girls themselves work extremely hard. It is in the nature of the pupils and the motivation that is engendered in them.
"What is interesting about the pilot project is they have moved away from whole-school averages and looked at the results for individual pupils because they are the people that really matter.
"In terms of value added, this looks a well-considered, measured way of doing it but I would like to see what other people think as well. I would like to look at the evaluation of the pilot. If you are going to have a table, the more complete the range of information you produce the better."
The school has been setting its own targets for pupils since 1994 using a system of target minimum grades. KS 3 results are used to give pupils GCSE targets. Those targets are revised annually while progress is monitored each term.
The pilot scheme is an extension of the data gathering already in place for the school's in-house monitoring of achievements.
Mr Phillips said: "The fact we were included in the pilot was easy for us.We have been looking at ways to boost our achievement by looking at setting targets for students. We look at data to try to set an expectation of what students might achieve in the future."
Ms Day said: "We will continue to look at ways of gathering information that will raise expectations and continue our trend upwards. It is also rewarding for the teachers to actually have some feedback other than the raw scores - to know they are making a difference because we believe here teachers do make a difference. To have some measure of that is good."
The pilot project compared performances at KS3 and GCSE. Mr Phillips said the pilot scheme required little extra work for teachers because the results were already being collated.
There were 183 pupils in the year but the pilot scheme looked at the GCSE results of 87 per cent of them. The large number of refugees in the school means a high mobility rate - that is the number of children moving on from the school. "There is a lot of coming and going," said Ms Day.
The complete secondary school amp; college performance tables are published in a 40-page special section in today's TES.