New 'super grammar' may break the law, Gove is told: Expansion could be stopped as they breach rules that mean no new grammars can be built Two grammar schools have submitted rival applications for an "annexe" which could take up to 1,300 pupils Kent council approved the applications which were then sent to the Department for Education five months ago Mr Gove has not made a final decision because lawyers are checking if they breach rules that allow grammar schools to expand but bans new ones If the plans are approved it is expected to open the floodgates for similar applications by other local authorities Concerns: Michale Gove is having to delay his decision while lawyers check if the plans breach rules which ban new grammar schools Plans for the most significant addition to the grammar school sector in 50 years are being stalled by Education Secretary Michael Gove because he is concerned they are illegal. Two grammar schools have submitted rival applications for an "annexe" which could take up to 1,300 pupils. The vast site in Sevenoaks, Kent, will have its own staff, although it will share a headteacher, department heads and answer to the same governing body. Kent council approved the applications which were then sent to the Department for Education five months ago. But Mr Gove has not made a final decision because lawyers are checking whether they breach rules that allow existing grammar schools to expand, but ban new ones. If Mr Gove eventually approves the plans it is likely to open the floodgates for similar applications by other local authorities. He will also face accusations from Labour that he is expanding the selective system by the back door and condemning children who fail the 11-plus exam to a second-rate education. In a letter to Sevenoaks Tory MP Michael Fallon last month, Mr Gove wrote: "We must judge the proposals carefully to test whether they represent new schools or expansions." A Kent County Council spokesman said: "It's a first which is why there has possibly been a delay. It's like a completely new school. Dr Phil Limbert, chief executive of Valley Invicta Academies Trust, which is behind one of the bids which would expand Invicta Grammar in Maidstone, added: "It's bound to be a politically difficult decision. It is the first significant move forward since the last new grammar school opened in the 1960s. Weald of Kent Grammar in Tonbridge is the other applicant. The details emerged after Sir John Major reignited the debate around social mobility this month. The former prime minister, who went to a grammar school, said it was "truly shocking" that the privately educated dominate politics and influential professions. Supporters of selective state education say it is one of the most effective means of improving social mobility. Kent, which is fully selective county, meaning all children have the opportunity to take the 11-plus, has 101 secondary schools, including 32 grammars. A surge in births means it must find thousands of extra places over the next few years. The pressure is particularly acute in Sevenoaks where there are no grammars, meaning children have to travel more than 30 miles a day to get to the nearest selective school. It is hoped the new site would start taking pupils by September 2015. There would be around 180 places each year for 11 to 16-year-olds and a sixth form for another 300 to 400 pupils. In 1947 there were 1,207 state-funded grammars in England teaching 37.8 per cent of secondary school pupils. Choice: Kent is a fully selective county meaning all children have the opportunity to take the 11-plus and has 101 secondary schools, including 32 grammars Labour introduced legislation abolishing grammar schools in the 1970s and by the middle of the decade there were just 675 catering for 12 per cent of children. A record low of 3 per cent was reached in 1986. Since then, the 164 remaining grammars in seven fully selective local authorities and 29 partially selective areas have managed to increase their share to 5 per cent through expansion. New admission rules introduced in 2011 stated councils could no longer block the expansion of existing schools - whether comprehensives or grammar. Sarah Shilling, of the Sevenoaks Grammar School Campaign, said: "When Michael Gove said well-performing selective grammar schools could expand in the same way as good non-selective schools, I don't think he realised what he was saying." A Department for Education spokesman said: "We believe strongly that good schools - including grammars - should be able to expand. The law prohibits the establishment of a new selective school. We are currently assessing proposals for a site in Sevenoaks. No decision has been made.