Classroom standards at Kent’s primary schools are to come under the spotlight in a county council investigation examining why many appear to under-perform.

A cross-party group of county councillors are to carry out an inquiry aimed at establishing why Kent persistently lags behind the national average when it comes to league table results.

Among factors likely to be considered are whether the 11-plus adversely affects standards.

Some have argued pupils may not be as focused on the Key Stage Two tests once they know if they have secured a place at a grammar school.

Cllr Chris Wells, the inquiry chairman, said councillors intended to take evidence from a range of witnesses, including pupils themselves, teachers and other experts.

He said: "We appear to have lagged behind the national position over a sustained period of time and the intention is to take a real close look at a series of schools that are doing well and others that are doing less well to try and understand why they are doing differently.

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"It is a question of working out whether there are lessons that can be learned."

It was not a matter of schools in poorer areas doing less well as there was evidence that many excelled despite serving disadvantaged communities, he added.

"That can be a common assumption but I think it is wrong. There is a lot more to it than that.

"If you look at the top 50 primary schools, there is a real mix in there."

The possible influence of the 11-plus test, which pupils take before their SATS in May, would also be considered.

"It is not something we are going to walk away from. Taking the 11-plus earlier is something that some teachers do say has an impact and changes perceptions but I know the issue is much wider than that."

According to the most recent league table results, primary standards in Kent improved in 2010 but remained behind the national average.

Ninety of the county’s 436 primaries - nearly one in four - failed to reach the government’s new tougher target for 60 per cent of children to reach Level Four - the national benchmark - in English and maths combined.

The inquiry’s findings are due to be delivered later this year and hearings begin next month.