There are always discussions about the need for more or less grammar schools in the UK, but a new study shows these schools might not be any better.

Attending a grammar school may not automatically improve a child’s chances of scoring good GCSE grades, according to the study.

It suggests the type of school a child goes to has little impact on their academic achievement.

The study, by researchers at King's College London (KCL), is based on an analysis of more than 4,000 students in England and Wales.

It indicates pupils who go to selective (grammar and private) schools are genetically more likely to do well in exams.

Looking at GCSE results, the researchers found students at private and grammar schools scored around a grade higher across English, maths and science than their peers in non-selective schools.

But once factors involved in selection are taken into account - like ability, previous academic achievement and socio-economic status - there was less than a 10th of a grade difference in results.

Lead author Emily Smith-Woolley said: "Our study suggests that for educational achievement there appears to be little added benefit from attending selective schools."

She added: "Although school type appears to have little impact on achievement at GCSE, there are many reasons why parents opt to send their children to selective schools.

"Further research is needed to identify if school type makes a difference in other outcomes, such as university and career success."

Controversial proposals to lift the ban on creating new grammar schools were a key to the Conservative manifesto in last year's snap general election, but the plans were dropped in the wake of the election result.

But grammars can still take on more pupils under rules that allow good state schools to expand.