A grammar school could be set to open in Croydon for the first time in decades.

Wallington Country Grammar School (WCGS) revealed plans to open an "annex" site in the borough after being boosted this week by the Department for Education's approval of a new selective school in Kent.

Weald of Kent school in Tonbridge side-stepped a ban on grammar schools to win consent for a new site in Sevenoaks - which will be the first new grammar school in 50 years - on Thursday.

Jonathan Wilden, headteacher of WCGS, in Sutton, said he hoped the news would be the catalyst for plans to expand his own school, which has a yearly intake of 120, into Croydon South by 2019.

He said: "The news of the grammar school annex in Kent being approved is exciting for the WCGS Academy Trust, who run Wallington County Grammar School, as this is an opportunity to expand their existing four form entry school and meet local demands for residents in the Croydon South area. 

"There is not only a shortage of school places in this part of the borough but also a huge desire for selective education."

The proposed new grammar school would be separate from WCGS's plans for a non-selective free school in Croydon, which were approved by the Department for Education earlier this year.

Thirty per cent of WCGS's pupils are from Croydon, which has no grammar schools.

Chris Philp, Croydon South MP, supports proposals for a grammar school in his constituency and has held talks with WCGS.

He said: "This is obviously a big boost for that campaign and it has got a step closer to becoming a reality with this week's decision.

"We have been watching the Sevenoaks case very carefully. We have been discussing the concept, we have been discussing potential sites. It's now a question of pushing forward these plans now the Government has indicated they are willing to sanction new grammar school sites."

Labour, which introduced legislation barring new grammar schools in 1998, described the announcement of the Sevenoaks school as a "hugely backward step". 

Mr Wilden admitted WCGS's plans would "attract much debate" but said he hoped many would support the new school.

Mr Philp, who attended St Olave's Grammar School in Bromley, said non-fee-paying selective school gave parents greater choice.

He added: "What grammar schools do is give children from ordinary backgrounds the chance to acheive their potential. 

"It's something I've got experience of - I was offered a place at Trinity in Croydon but even with a scholarship my parent's couldn't afford to pay the fees so I went to a grammar school next door in Bromley.

"Without that grammar school I wouldn't have got to Oxford and I certainly wouldn't be Croydon South's member of Parliament."

The DfE approved Weald of Kent school's new site in Sevenoaks after accepting it was an extension of the current school, although the two locations are 10 miles apart.

Education secretary Nicky Morgan insisted it would not "open the floodgates" to more selective schools, describing it as a "genuine expansion" of an existing school.

WCGS's plans to open a separate free school in South Croydon won Government approval earlier this year. 

It is looking at sites in Portnalls Road, Coulsdon, and Waddon as potential locations for the grammar school.