A bid by a Kent grammar to open a satellite school is nearing approval with the education secretary expected to grant permission, it has emerged.
The Weald of Kent girls' grammar school wants to open the annex in Sevenoaks.
Earlier bids for an annex were turned down but the BBC understands this one meets legal requirements for approval.
The Department for Education confirmed it had received the proposal and was giving it careful consideration before making a decision.
The government rejected earlier proposals for Kent grammar schools to open annexes on the same site on the grounds that they did not comply with the law.
The law forbids the opening of new grammar schools, but changes made by the coalition government in 2012 allow enlargement of existing schools.
Kent County Council has said it believes the new bid to expand the girls' school complies with the regulations in a way that previous bids for a mixed annex did not.
It has already granted planning permission for the annex if Education Secretary Nicky Morgan approves the scheme next month.
Sevenoaks is the only major Kent town which does not have a grammar school.
Bids made last year by Weald of Kent and Invicta Grammar were turned down because the DfE said neither complied with the law.
The plan is for the annex to admit 90 pupils a year from 2016.
Weald of Kent school has 1,200 pupils of whom about 500 travel the seven miles from Sevenoaks.
If approved, the annex could pave the way for more grammars to open satellite campuses.
Proposals include a consultation by the Royal Borough of Windsor and Maidenhead on whether to invite a grammar school in neighbouring Buckinghamshire to open an annex in the town.
Last month, the consultation gained the backing of Home Secretary Theresa May who is the MP for Maidenhead.
The move towards an expansion of selective education is likely to have the backing of senior Conservative MPs who want the party's election manifesto to include a pledge to increase the numbers of grammar schools.
Christine Blower, general secretary of the National Union of Teachers, called the plans "yet another unnecessary distraction".
"Not content with breaking up the education system into an incomprehensible patchwork of unaccountable academy chains and free schools, the government is now contemplating throwing grammar schools into the mix.
"Academic selection at 10 or 11 years old is simply wrong. International evidence from the OECD clearly demonstrates that if an education system is to be characterised by quality and equity, it is the comprehensive path that must be followed."
Ms Blower said evidence from the UK showed that in grammar-school areas children in neighbouring secondary modern schools did less well than their peers in fully comprehensive schools.