One of the remaining local authorities in England still committed to grammar schools has commissioned researchers to find out if the selective system is behind its stalled KS2 Sats results.
Slough Borough Council is determined to know why its results for the national tests have remained below par for several years.
A team from the National Foundation for Educational Research will assess whether one explanation is the widespread use of out-of-school coaching for the 11-plus, which often bears little resemblance to the primary curriculum, and the effect of failure in these exams on self-esteem.
Four of the 11 secondary schools in the town are grammars. Children wanting to go to these schools take the 11-plus in the autumn term of Year 6. The most popular 11-plus test in Slough is a verbal reasoning test, which is not related to the primary curriculum.
Clair Pyper, director of children's services at the council, said there was no intention to get rid of grammar schools.
"What we want to know is if the 11-plus selective system has an impact on the results in Slough, whether the 11-plus proves a distraction and whether it impacts on pupils' self-esteem."
However, she added: "Grammar schools are part of the range of schools we have in Slough."
Static KS2 results lead to earlier study
The research follows an earlier study into the wider reasons behind the static KS2 results, which was commissioned last year.
The researchers, Claire Easton, Peter Rudd and Simon Rutt, found that in recent years the ethnic make-up of the city had changed, with increased numbers of Somali and Eastern European pupils moving in.More than half the city's primary-aged children do not speak English as their first language - and in one school 95 per cent of pupils were non-English speakers. Most schools had at least 30 languages spoken.
The researchers pointed out that individual pupils' progress was as expected.
There was no difference between pupils in Slough and similar pupils in similar schools in Luton. Schools were good at settling in children who were new to England and the quality of teaching and emotional well-being was good.
Mrs Pyper said that as well as looking at the role of the 11-plus, the council would focus on inclusion, mobility and attendance. But she added that the Government should be realistic about what could be achieved.
She said: "We are judged on the key stage 2 results, even if we have good schools. The trajectory the government wants is continuous improvement. We have the highest possible aspirations for pupils in Slough, but we need to be realistic about what children can manage and schools can manage.
"I would defy any of us to move to another country where we don't have the language and are new to the curriculum and then make the same progress expected of children who grew up there.
"The cost of supporting these children isn't anywhere near met by the money we have in the schools budget or the local authority budget."