The all-girl Green School, in Isleworth, has applied to open a boys’ secondary school.
The Green School for Boys would open in September 2016 and would have 1,260 pupils aged 11 to 18 by the time it reaches full capacity in 2023, should it get the go-ahead.
Directors of The Green School Trust submitted an application to the Department for Education this month and are due to hear whether it has been successful by late April.
The proposed opening date for the new school has been pushed back 12 months since plans were originally announced last year, but most of the other details remain the same.
It would be a free school, meaning it is independent from government control, and would ideally be located within a mile of the girls’ school in Busch Corner, though a precise location has yet to be confirmed.
It would be a Church of England school, but would accept a proportion of pupils from other backgrounds.
The Green School’s interim headteacher Jill Coughlan said: “The Green School for Boys will provide a boy-friendly learning environment with a broad curriculum which also focuses on science, technology, engineering and mathematics.
“Many of its systems and practices will be developed from those that have been so successful at The Green School for Girls.”