A campaign group has slammed MP Dominic Grieve for his “ill-informed and misleading” support for expanding a Marlow grammar school in to Maidenhead, claiming pupils are being failed by the Bucks education system.

Last month Mr Grieve said he would be entirely supportive of Sir William Borlase Grammar School if it decided to create an “annex” school in Maidenhead, also praising the Bucks education system for being the best in the country.

However Local Equal Excellent – a group campaigning against “selective” education –claims the achievement gap for Bucks pupils is in fact one of the worst in England and the expansion of a grammar school would just replicate the county’s failures.

Derek Berry, from LEE, said: “Dominic Grieve’s claim that the overall level of education in Bucks is ‘one of the highest in the country’ is ill-informed and misleading.

“A recent independent report actually found that Bucks has one of the biggest attainment gaps in England.

“And government figures suggest that middle-attaining children in Bucks do worse than they would be expected to do in a comprehensive system.”

The debate on grammar schools reared its head after Borlase announced it was exploring the option of a satellite school in Maidenhead, mirroring plans for a ground-breaking “annexe” school in Kent revealed last year.

However LEE branded the 11 plus test as “discriminatory” against families who are unable to afford tuition, after contrasting the 22 percent pass rate of Bucks state school children with 60 percent pass rate of independent schools in the county.

It also said figures show that Bucks GCSE results are significantly lower than those in the Royal Borough of Windsor and Maidenhead, with 50 percent of  middle level children from Bucks uppers schools achieving five A* to C's compared with 62 percent in the RBWM.

Mr Berry continued: “The evidence available on the Department of Education web site confirms that Bucks overall results especially for middle and low attainers are much lower than the Royal Borough of Windsor and Maidenhead (RBWM) schools.

“The 2015 Key Stage 4 results indicate that if Bucks had the same achievement levels as the RBWM schools, an additional 250 + Bucks pupils would have achieved the 5 A*-C GCSE including Maths and English.

“Mr Grieve's support for extending a Bucks Grammar School into the RBWM needs to be questioned. The possible consequences for RBWM schools could be very damaging.

“We have offered to share with Dominic Grieve the wide-ranging evidence that shows how selection is failing the majority of our children in Bucks.”

A progress review of the exploration of an annex school by the Royal Borough of Windsor and Maidenhead is due to be presented at the cabinet meeting on Thursday, April 28.